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Laying a concrete slabe
FOR A STRONG PRODUCT, KEEP FRESH CONCRETE MOIST AND WARM FOR AS LONG AS POSSIBLE
BY DAVID CARNS
Most construction projects call for concrete in some form, whether as footings, walls, or flatwork. As a frequently used material, concrete is also a common source of problems. Foulups can occur at any stage, from batching, mixing, and transporting to placement, finishing, or even curing, the final step. Concrete that has been handled correctly all along can still be ruined if it's not properly cured.
Warm and Wet: Keys to Curing
Curing means taking steps to keep the concrete under the right temperature and moisture conditions during the first few days of hardening after placement. Proper curing is vital because the concrete will eventually be much harder and stronger if it is cured correctly.
Hydration. The hardening of concrete is not a drying process, but rather the result of a chemical reaction between the finely ground portland cement particles and the water in the mix. This reaction is known as hydration. Like most chemical reactions, hydration is greatly influenced by temperature. The basic idea behind proper curing is to allow this reaction to continue as long as practical by maintaining a suitable curing temperature, usually 50°F to 90°F, and by keeping the concrete wet. If the temperature of the concrete drops below 50°F, hydration begins to slow, and if the water in the mix freezes, the concrete will be ruined. Also, if too much water escapes from the concrete, hydration will stop altogether. The longer favorable conditions are maintained, the longer the concrete will cure, resulting in a better product.
Benefits of Good Curing
Although it may require some extra effort on the average residential job site, maintaining proper curing conditions will result in superior concrete. Properly cured concrete has several desirable qualities:
It is stronger in compression (see
"Moist-Curing for Maximum
Strength," next page).
It resists abrasion much better. This is important for concrete floors and pavements. o It is more durable; in particular, it is better able to withstand repeated freezing and thawing over the years.
It is less permeable. This makes a
big difference in concrete walls designed to keep out moisture, such as basements.
A note of caution
Keep in mind that proper curing will not compensate for poor quality concrete. Concrete that is poured too wet will be weak regardless of how it is cured. Not all of the water that is added to the concrete mix is necessary for the hydration process. In fact, the amount of water required to completely hydrate the cement is only about one half to two thirds of what is usually added at the batch plant or on the job site. The rest is added strictly to make the mix more workable. Adding too much water, however, might save work during placement, but it will also result in very weak, porous concrete, even with proper curing.
How and When to Cure
Hydration begins as soon as the cement particles come in contact with the mix water. Curing begins immediately after placement, or in the case of flatwork, immediately after the final finishing is done. You should move quickly to create suitable curing conditions. Even when the temperature is within the 50°F to 90°F range, you need to prevent evap- oration from the concrete by sealing it or keeping it wet. If hot, dry, or windy weather is likely to cause excessive evaporation, or if cold temperatures threaten to freeze the concrete, the need to control temperature and moisture becomes even greater. For milder weather, here are some techniques that work well on residential job sites:
Slabs and flatwork
You can keep a slab wet with a continuous water spray, such as a lawn sprinkler. This provides the moisture necessary for the slab surface to properly cure, and cools the slab to slow evaporation during hot weather. However, you have to keep an eye on things, which isn't always practical. I remember one time when a homeowner came home and helpfully turned off the sprinkler, thinking that the contractor had forgotten about it. The slab dried out and curing stopped.
You can dam the edges of a slab with dirt or plastic and pond the surface with water. This works fine in theory, but it has the same drawback as the water spray: You have to keep watch.
You can also cover a slab with polyethylene sheets. Use clear poly, 4 mil or heavier. Do not use black poly, especially in hot weather. The idea is to keep the moisture contained in the concrete from evaporating. If the plastic has even small holes or tears, or if a tight seal is not maintained around the edge of the slab, moisture will escape and curing will stop. Tape the plastic to any protruding rebar or plumbing, lap and weight any seams, and weight all the edges. This method is practical and inexpensive, and works well when the poly is completely sealed.
There is one drawback: Where the plastic makes contact with the concrete, it can discolor the slab surface. If appearance is important, consider one of the other methods. Curing compound.
You can apply a curing compound. These commercially available compounds provide a thin sealing film that accomplishes the same thing as a plastic sheet, holding moisture in the concrete. These compounds may be either clear or pigmented; with the pigmented product, you can tell where you've sprayed. They are relatively inexpensive - a gallon sells for about $8 and covers 200 to 300 hundred square feet. A garden sprayer works well for applying the compounds. Usually two coats are recommended, the second at right angles to the first, to ensure complete coverage. Keep in mind that all surfaces should be coated, including slab edges.
Although curing compounds will eventually wear off, some will prevent adhesion of paint, carpet, vinyl cements, or future concrete. Consult your supplier if this is a consideration. Curing compounds are widely used on both residential and commercial jobs, with good reason. They are easy to apply, inexpensive and effective, and they require little or no attention once applied. Best of all, you can use the slab as soon as it has cured enough that it won't be easily damaged.
Formed concrete
The best way to cure formed concrete walls is to leave the forms in place as long as practical - a minimum of three days is best. The formwork holds in moisture and, in cold weather, heat. In hot weather, keep the forms hosed down to control temperature and reduce moisture evaporation from the concrete. Any exposed concrete, such as the top of a concrete wall, should be covered with plastic or sprayed with curing compound. If the forms are stripped earlier than three days, the concrete should be either covered with plastic for several days or sprayed with curing compound. There are some obvious practical considerations here. The idea is to allow the concrete to cure for a reasonable length of time, yet not delay the rest of the job.
How Long to Cure?
The answer to this question is the longer the better. Concrete will continue to hydrate and gain strength almost indefinitely as long as moisture is present and a suitable temperature is maintained. Try drilling or jackhammering 30-year-old concrete and you'll see what I mean. If concrete is cured in cool temperatures (32°F to 50°F), strength gain will be slow but the concrete will eventually reach a high strength as long as moisture is continuously present. However, concrete should not be allowed to get hotter than 90°F or to dry out during the curing period. If the concrete dries out too early in the hydration process (within the first three days), long-term strength will be compromised even if moist conditions return. If your intention is to produce the highest quality concrete, keep freshly poured concrete moist at 50°F to 90°F for seven days for Types I or II portland cement ("regular" concrete) or for three days if Type III cement (highearly, or rapid-hardening) or accelerators are used.
As a practical matter, though, most concrete subs strip their wall forms after a few days, and few builders take the trouble to continue the curing process beyond that point. This is usually not a problem since, after curing for a few days behind the forms, 8- inch-thick concrete walls are plenty strong to carry residential loads (though you have to be careful about backfilling too soon). For slabs, though, with their increased surface area, you should pay more attention to curing, especially since conspicuous surface defects may be unacceptable.
Hot Weather Curing
The biggest problem in hot weather is excessive moisture loss from the concrete surface (see "Bad Weather Curing," facing page). This can be serious for thin concrete members, such as slabs, that have a large surface exposed to the weather. Surface evaporation is affected by a combination of four factors: concrete temperature, air temperature, relative humidity, and wind speed. Placing concrete in hot weather is complicated by the fact that the hydration reaction generates heat, adding to the problem of excessive evaporation.
Crazing
If you pour a slab on a hot, windy day without proper precautions, several defects can result. One defect, known as crazing, causes fine surface cracks in a chicken wire pattern that are especially visible if the slab is dampened. Crazing results from too much surface evaporation during the initial curing period. It is a cosmetic problem, not a structural problem. Applying a curing compound or sealing the slab with plastic helps to prevent crazing; this should be done as quickly as possible after the slab is finished.
Plastic shrinkage cracks
A more serious problem, plastic shrinkage cracks, can happen when moisture evaporates from the slab while the concrete is still "plastic" - that is, wet and workable. This typically happens on a windy day, leaving short, parallel cracks (6 inches to 3 feet long) at right angles to the wind. Plastic shrinkage cracks can allow water to enter an outdoor slab, where it may freeze, causing further deterioration.
Under extremely hot, dry, and windy conditions, you may not be able to prevent crazing and plastic shrinkage cracks; it's best to pour early in the day or wait until conditions improve. You can also use set retarders to slow hydration, and some batch plants may offer ice as a replacement for part of the mix water.
Lower strength
Furthermore, excessive evaporation will lower the final strength of the slab, since hydration may not resume once moisture is again present. A slab that is not sealed with plastic or a curing compound must be kept continuously wet throughout the initial curing period if it is to achieve full strength.
Cold Weather Curing
Placing concrete in cold weather gives rise to two concerns: Strength gain is slowed because hydration slows, and the water in exposed concrete may freeze. Job specs often require concrete to attain a specified strength before use or form removal; in that case, slow strength gain may slow the job's progress. On the other hand, if moisture in curing concrete is allowed to freeze, the result can be weak, poor quality concrete or spalling (flaking) of the slab surface. The more freezing cycles the wet concrete endures, the worse the problem. Freezing becomes less of a concern after the first few days, tion process continues to reduce the moisture in the concrete.
Heat of hydration
Often the "heat of hydration" will help speed coldweather curing. Insulating blankets, straw-covered plastic, insulated forms, and windbreaks will all help retain this internal heat, speeding strength gain and preventing freezing. Accelerators or Type III cement can also be added to the mix at the batch plant to speed curing. This won't cause more heat to be released overall, but it does result in more heat being released during the first few days when maintaining concrete temperature is most critical. you use an accelerator, try to avoid the calcium-chloride type; the chloride tends to corrode reinforcing steel.
Enclosures
Heat can also be added to the concrete by building temporary enclosures of polyethylene or canvas and using a kerosene or propane "salamander" heater. Combustion heaters should be vented outside the enclosure, however, because carbon dioxide in the exhaust will react with and soften the concrete surface. Also, in colder regions, ready-mix suppliers are often set up to heat either the mix water or the aggregate, or both, as is the case here in central Washington.
Common sense
Protecting concrete in cold weather becomes a function of the air temperature and common sense. If, for example, you pour a slab when it's 40°F outside and weather forecast calls for temperatures to drop to the mid-twenties night, covering the slab with an insulating blanket for the first night should keep the concrete warm enough until the next day, when blanket can be removed as it warms up. If it's already below freezing when you pour, and the forecast calls lower temperatures to come, keep concrete covered or heated for least several days. The major concern is to prevent the moisture in the concrete from freezing during the initial curing period.
Although concrete gains strength more slowly at lower temperatures, the strength of concrete cured at will eventually reach that of concrete cured at 70°F. Even if the concrete temperature drops to the mid teens, the hydration process will continue a very slow rate.
David Carns, P.E., teaches engineering at Central Washington University, Ellensburg, Wash.
Brick Laying
Tools:
Bricklaying trowel
Spirit Level
Builder's square
String line
Shovel
Bucket
Hammer
Bolster
Measuring tape
Wheelbarrow
Pencil
Materials:
Bricks
Clean sand
Cement
Lime or plastizer
Tips
1 Metre square of wall = approximately 50 bricks.
Order 10% more bricks to allow for wasted or broken bricks.
Preparation
Erect a secure profile on each end of the proposed wall. This profile should be pre marked with the height of each course of bricks and the mortar joint.
Scratch a marker line / corner on the concrete foundation. This line comes from the profiles which we erected at the start.
By stringing a line between the profiles you can drop the line down onto the concrete with the aid of a sprit level and a length of wood, held plumb against the line.
(a brick is usually 75mm high + a 10mm joint = 85mm) Please check the bricks as they can vary from one supplier to the next.
*Make sure the profiled courses are level.
String a line between the profiles and lay your bricks.
When laying the bricks, make sure that the bricks do not touch the line.
Mixing mortar
Mortar can be mixed on any hard clean surface near the site. Start by mixing four shovelfuls of sand to one shovelful of cement and one shovel of lime, turning this over with the shovel until it is well mixed.
Form a hole in the middle of the mortar mix, and add a little of the water. Turn the mixture carefully, adding more water as you go along. When the mixture is firm but wet it is ready.
You can also use plastisizer in place of lime. - Follow the directions on the bottle.
Gauging
The success of a brick structure depends a great deal on the continuity of its gauge - the ideal width of the mortar joints between the bricks is 10mm. It may not be possible to achieve this on your first course, but great care must be taken to get as close as possible to this on subsequent courses.
Cutting bricks
Bricks will inevitably have to be cut to achieve a proper bonding pattern. To do this, place the brick on its side on a solid surface. Using the bolster, make a groove about 1mm deep around the brick. Keep the bolster as upright as possible, and hit it hard with the hammer.
Using a trowel
It may make your life easier (and save a lot of mess) if you practice this a few times with no mortar!
Arrange the mortar in a neat pile on one side of the blockboard. Using the trowel at an angle, pulled towards to you, cut a section of mortar, and roll the mortar towards you smoothing it to form a "sausage" with pointed ends. (This is known as a "pear") Pick it up by sliding the trowel underneath it and up in one movement.
Laying your first course
Begin by arranging the bricks which will make up the wall without using mortar, leaving about a 10mm gap between each one.
*(A brick is 220mm long + 10mm joint = 230mm)
Before you lay the first brick wet the foundation
(this slows down the suction between the brick and the mortar)
The bed of mortar should be laid about 12mm deep, which will flatten out to 10mm when the brick is laid.
Pick up the first brick and place a pear of mortar in its place and flatten it out to the size of the brick. Make a depression in the middle of the mortar before you place the brick on it, to ensure an even spread.
Lay the brick and tap it down with the trowel (this helps the brick and mortar to 'suck' together).
As you lay the bricks, check with the string line that they are in line & level, or use the spirit level and tap them as needed. Continue checking as you go.
Laying further courses
When the course / row is complete lift the line on the profiles and continue.
IMPORTANT
Do not lay more than 1.5m high in a day as this will cause the joints at the bottom rows to compress which in turn will affect the lines of brickwork. (roughly 17 courses)
When laying the next course, make sure that the mortar completely fills and covers, the vertical joint - 'perp' of the first course.
Make sure that the brick is -half a brick along-, so that the vertical joint is in the middle of the previous course.
It is very important to keep checking the level of the bricks and that the alignment is correct at all times - this cannot be done often enough!
Turning a corner
Use the builder's square to make sure that the angle of the corner is correct.
You can also check for square by the good old Pythagoras method. Also known as the 3,4,5 method.
Use any unit of measure, be it metres, yards or feet.
Starting from the corner that you want to be 90 degrees.
Measure the one leg / wall 3 metres the other wall 4 metres and distance between the end points should be 5 metres. If it is then your corner is 90 degrees.
But this should have been done when you placed the profiles. See setting out foundations.
After laying the corner brick, butt the level up against the heel of the end brick, and tap the corner brick into place.... And carry on laying.
Finishing the joints
To improve the overall appearance of your project, you should finish the joints about 30 minutes after they have set - this will also protect the mortar from erosion.
To get a "round tooled" finish, rub the joints with a rubber hose, about 12mm in diameter, along the half-dry joints, and brush away the excess mortar.
Do the vertical joints first and then the horizontal.
Carpentry
Essential Tools
Claw hammer
Get a good one. I would recommend one with a fibre shaft with a rubber grip. It absorbs the shock and is firm in your hand. Usually a lot stronger than those cheap wooden handled hammers. BUT it is not essential to have a fibre handled hammer.
Tape measure
5m is long enough. A 3m tape is not long enough and it is usually a lot thinner which means harder to read.
Screwdrivers
A 'normal' screwdriver and a "Phillips" or star screwdriver. A set of "Posidriv" screwdrivers. Pay attention to the 'handle' as this will be the first to break.
Sundry small tools
Utility knife with extra blades.
Chisels, I would recommend you have at least a 12mm and a 20mm.
Drill bits, You might as well get the pre-packed box.
Sanding block.
Mitre box
Pinchers to remove nails without heads.
A course Rasp and a file.
Sprit level
At least 600mm This will allow you to use it as a straight edge for marking off as well. The new ones are all the same. An aluminium box section with a "bubble box" inserted.
Saw
Here I recommend a "Crosscut" saw.
When sawing you use the whole saw not just the middle bit. When you use a long stroke it is easier and more relaxing therefore you will saw straight.
Drill
Well I cannot see a way around it. We want to do the job quickly and with the least amount of effort, so go electric. The drill should be at least 450W (that's the power, 600 Watts would be better) with an impact selector switch.
I recommend reversible and with a variable speed. This is good should you want to use it as an electric screwdriver or drilling in tiles. It allows for a slow start.
Tool box
Use a sectioned tool box for safety and keeping your tools sharp.
Work bench
Not really necessary, a work mate type stand is good enough to start with.
FIXINGS.
Nails and Screws
Nails and screws are the two most important fixing devices used in carpentry, and there are many different types. Here we give you break down of the more common types, and their uses.
NAILS
Nails are seldom driven in straight - a stronger joint is made if they go in at an angle.
A very strong joint can be achieved if two nails are driven in opposite directions, and a woodworking adhesive is used as well.
When nailing two pieces of wood together, always nail the smaller to the bigger.
To drive a nail into hardwood, first drill a hole slightly smaller than the shank of the nail.
Round wire
This is used for rough carpentry work - it has a large ugly head that ensures a firm grip, but can split wood.
Oval wire
This commonly used nail makes it unlikely to split the wood if the long axis follows the grain.
Masonry nail
This is a hardened steel nail used to fix wood to soft bricks or concrete.
Lost head
The head of this nail can be punched below the surface, and the hole filled to hide it.
Hardboard pin
This has a special head shape that sinks itself into hardboard and can be filled over.
Panel pin
This is a small nail used for fixing light pieces of wood together, usually with the aid of glue.
Clout nail
This large headed nail is galvanized for outdoor use. It is mainly used to fix roofing felt and wire fencing to wood.
Flooring brad
As the name states, it is used to nail down floorboards. It has good holding power and is unlikely to split wood.
SPECIAL-PURPOSE NAILS.
Carpet nail
This is a small nail with a broad head used for fixing carpets and fabrics to floorboards or wood.
Annular nail
This nail has a very strong grip and is used to fix plywood and other sheet materials. It is difficult to remove.
Roofing nail
This galvanized nail is used for outside work, such as securing corrugated iron or asbestos to wooden rafters.
Pipe nail
This nail is used to fix guttering and other drainpipes directly onto bricks or masonry.
SCREWS
Always ensure that the tip of your screwdriver is in good condition and that it fits the slot of the screw head exactly. If the blade is too narrow or rounded it will damage the slot, and if it is too wide, it will damage the wood as the screw goes in.
To make screw driving easier, the screws can be rubbed with some candle wax before working with them.
To prevent damaging a brass screw when screwing these into hardwood, drive in a steel screw of the same size first. (Brass screws are quite soft)
Countersunk screw
The head of this screw sinks in flush with or slightly below the wood surface, and is used for general woodwork.
Pozi or phillips screw
This screw is used for general woodwork, but needs a special screwdriver, which does not slip from the head.
Countersunk roundhead screw
This is used to fix door-handle plates and other decorative fittings with countersunk holes. The head is designed to be seen.
Roundhead screw
This is used for fixing hardware fittings without countersunk holes and the head protrudes from the work.
Mirror screw
This is used to fix bathroom fittings and mirrors - the chromed cap threads into the screw head to hide the screw. Do not over tighten.
Invisible screw
This is used to join two pieces of wood without being seen.
Panel screw
This is used for fixing thin sheets of metal and plastic, and cuts its own thread as it is screwed in. There are different types of heads available.
Chipboard screw
This is used to secure chipboard and other similar materials.
Fixing and replacing floorboards.
Floorboards, although solid and hardwearing, are prone to all sorts of minor irritations and faults. Repairs are straightforward, and require few special tools.
Most floorboards are made of soft wood, usually pine, and are nearly always fixed at right angles to the joists which support them. They are either nailed or screwed into place. The board ends are arranged so that the join lies over the joist to give maximum support.
Households generally have either square-edged or tongue-and-groove types of floorboards. The latter are designed to eliminate draughty gaps, but are more difficult to remove than the square-edged type.
Tools
Bolster (100 - 150mm)
Claw hammer
Chisel (25mm)
Crosscut saw
Crowbar or wooden lever
Materials
Off-cut of softwood - to form a support next to joist
2 or 3 x 75mm long nails - to hold support in place
Caulking - to prevent draughts in tongue-and-groove boards
Off-cut of timber - to knit tongue-and-groove boards
50mm lost head nails OR 40mm counter sunk screws
Floor boards to match existing
Lifting square-edged boards
To start, choose the most convenient free end of the board you wish to lift. Should the board stretch across the room and under the skirting board on both sides, it may be easier to cut it at a convenient point so that the board under the skirting does not have to be removed.
To lift a board, insert a bolster into the gap (lengthways) between two boards, in line with the nails at the free end, using a claw hammer to hit it into position. Tread on the handle of the bolster, using steady pressure, and push this towards the floor. As the board is levered upwards, insert the claw of the hammer under the board and continue to lever it upwards until the board separates from the joist.
To lift the rest of the board, insert the crowbar underneath the free end, and using the bolster and hammer, loosen the the board at each row of nails, levering it clear with the crowbar. If a board proves to be particularly stubborn, try to free the end and insert the crowbar under it. Use the crowbar as a levering support. Stamp down on the free end, and after each stamp there should be some "give". Move the crowbar along the board towards the next joist, until these nails give way. As a last resort, cut the board free at the joist and chip off the remaining board with a chisel. Remove any exposed nails, especially those upright in the joists. Do not hammer these into the joists.
If screws have been used to secure the boards, these have to be located and removed to prevent these from ripping through the board when it is levered up.
There may be some damage to the edges of the boards when levering these up. If you plan to reuse these boards, then these edges can be planed smooth.
Lifting tongue-and-grooved boards
Before you start look at the floor. It is quite usual for this type of floor to be 'secret' nailed. The only way you can identify the joists - nails is by the end joints of the boards. The boards are nailed down on the side and above the tongue of the board.
Start as for the lifting of square-edged boards. To break the tongue, insert the bolster into the gap between two boards and give it a few sharp taps with the hammer until you feel or hear the tongue begin to split. Continue doing this until the split measures at least 75mm from the nails. You can now replace the bolster with a saw, knowing that the joists are safe from damage. Be careful not to saw to deeply as there could be pipes or wires running underneath the floorboards. Continue sawing until you are 75mm away from the next row of nails, and again use the bolster and hammer to break the tongue directly above the joists, and when you are 75mm past this, you can use the saw again. Continue alternating the cutting methods for the length of the board that you are removing.
Once the tongue has been fully cut off, use the bolster, claw hammer and crowbar to lever up the board as for lifting a square-edged board. In this case though, concentrate the levering along the side where the tongue has been removed.
Some tongue-and-groove boards may be very tightly cramped together, and in this case, splitting them apart using the bolster and hammer may not be possible without causing extensive damage to both boards. You have no alternative but to split the board that you want to remove lengthways down the middle. To do this, use a circular saw. Keep the cutting depth to less than the thickness of the board above the joists. Hammer the bolster into the partly sawn cracks to complete the split.
Fitting an extra support
This is done to provide extra support for the new board when there is no overlap over the joist.
Make the support from an offcut of softwood, the dimensions of which should not be less than 38mm by 50mm. Cut it slightly longer than the width of the board removed and either nail or screw it into place. If you choose nails, use two or three about 75mm long for each board width, and hammer these partially into the broad side before positioning the support. Should you choose screws, two for each board width are enough, but drill pilot holes before fitting them.
Position the support against the joist,and make sure that the top edge of both pieces of timber are level. Pull the support upwards, tightly against the floorboards on either side and hammer or screw the support into place.
Replacing square-edged boards
New boards are usually thicker than the original. Pay attention and have the supplier pass it through the thickness planner of the same thickness are cut to the length of the board being replaced, and in the case of non-standard width, to the same width. Should part of a board have to be tapered, use the old board as a template when the new one is being cut to size.
If a single board is to be replaced, simply slot it in and nail or screw it down, and if a number of boards are being replaced, each one should be done individually, and if possible, in the same floor "pattern" as before. Two adjacent boards should not end on the same joist.
Replacing tongue-and-groove boards
Replacing tongue-and-groove boards is a bit more difficult than square-edged boards. If you are using an old board, fit either the tongue or the groove into the adjacent board. There will be a small gap on the other side - this must be plugged to prevent any draughts.
A new tongue-and-groove board can be put in place only if the tongue that was cut off belonged to the adjacent board. Should the tongue that was cut off belong to the discarded board, the tongue of the new board has to be removed prior to fitting - this can be planed off.
When replacing a number of adjacent boards, old and new boards may be mixed. Loosely fit these together over the floor area to be covered, in the process forming a slight arch. Lay a spare piece of timber over this, and press or stamp it down. The tongues and grooves will knit together in the process. The flattened boards can then be nailed or screwed into place.
Dealing with creaking boards
Creaking floorboards may be caused by a number of reasons ranging from;-
Incorrect nailing.
The joists settling. - The floor has a spring in it or has sagged
Warping and shrinkage. - You will feel this as you walk on it
Wet or dry rot. - As for settling joists
If the board has dark black streaking on it then it is a good chance that the nail has rusted and stained the wood. It is logical that it will have affected the joist as well. Depending on how bad it is you might be able to fix a second joist along side the first. In this case lift a few boards to create a working area. It is important that you treat both the new and the old wood for rot. It is a simple paint on application.
A loose board can be nailed or screwed back into place, but make sure that the loose joint matches up with the centre of the joist below it. (If necessary lift the board to check.) If it does not match, you might have to fit a new support joist or replace the board.
To nail the floorboards, use 50mm lost-head nails. Position these next to and about 12mm away from existing nails. Make sure that all the nail heads are well below the surface of the nails.
If you wish to secure the boards using screws, use 40mm countersunk screws. Drill pilot holes for them 12mm from each existing nail, but make sure that the holes go no deeper than the thickness of the board. Make sure that all the heads of the screws are well below the surface of the boards.
Repairing skirting boards.
Skirting boards are used for a couple of reasons - to protect the base of the walls, as a decorative feature to hide the unfinished junction between the wall and the floor.
The traditional method of fixing the skirting is with the use of "grounds".
Strips of wood are attached to the wall and act as a fixing base for the boards placed over them. A continuous strip is supported at intervals by small upright pieces called soldiers.
In modern houses skirtings are fixed with masonry nails which are hammered at an angle through the board into the brickwork or with the advent of adhesives and glue guns stuck to the walls.
Tools
Bolster
Claw hammer
Saw
Mitre block
Timber wedge - for partial replacement
Materials
Offcut of wood
Masonry nails - or - Adhesive
Wood filler
Filler paste
Tips
One rule when skirting a room is that external corners are mitred and internal corners are scribed.
When the board is placed against the wall, small irregularities in the plaster may show - these can be filled with filler paste.
To remove skirting boards
To remove a length of skirting, start at one of the corners and place a bolster on the top edge where the skirting meets the wall. Using a claw hammer, gently hammer on the bolster, which will prise the skirting away from the wall at that point. (Insert the wedge and remove the bolster) Repeat this along the length to be removed. Where there is greater resistance, the skirting is nailed to the wall. To remove this section, place the claw of the hammer behind the skirting and slip an offcut of wood between the hammer and the wall (to protect the wall against any damage). Now lever the board away from the wall.
To remove a section of skirting board
Where the area of damaged skirting is relatively small, partial replacement may be more economical. Measure the section to be replaced and buy or make a replacement piece to match.
Prise the damaged section away from the wall using a bolster. With the top edge free, insert a timber wedge between the wall and the board where the first cut is to be made. The wedge should be thick enough to push the board out by about 40mm. The gap must be wide enough to permit sawing. Place a mitre block against the board and use the first few teeth of the saw to cut the wood. Move the wedge to the other end of the damaged area, and repeat the process. Any misfits that occur can be made good with a filler and then sanded smooth.
Fitting the replacement board
Using the mitre block, cut the desired length of replacement skirting board. Fit the replacement piece of board into the section and make sure that it fits snug. Plane down the mitres if necessary. Hammer the nails in skew, making sure that the heads are below the level of the board, and fill the holes with wood filler.
Matching new skirting board to old
Skirting comes in various types and sizes. Older houses generally have moulded skirting which are not always available. If a match is difficult to come by, one solution would be to fit a moulded architrave to the top of a square edged board.
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