Indy Total Construction

Solid concrete floors in modern houses are usually made up of a layer of gravel, topped by a layer of concrete (the subfloor), on top of which there is a waterproof membrane linked to the flashing in the base of the surrounding walls and finally a screed of mortar, which provides a smooth, level surface for your floorcovering. This type of construction is very tough, but even so, defects can occur; cracks, uneven surfaces and damp patches due to faulty waterproof membrane are all common problems.

Rotten wooden floors can be replaced with solid concrete ones relatively cheaply and they have the added advantage of providing a much more stable surface for laying something like quarry tiles or wood blocks. In this instance, however, you must incorporate pipe work air ducts to link any ventilation holes or grilles in the external walls with the suspended wooden floors in adjacent rooms.

If the surface of the floor is uneven you can smooth it with a self-leveling floor screed. Supplied in powder form for mixing with water or latex (depending on which it is based) the screed provides a smooth ‘Ain layer on which you can lay floorcoverings.

Pour small amounts of screed onto the floor at a time and trowel roughly level. There is no need to work out trowel marks, since they gradually settle out. Before you apply the screed you must remove the baseboards and make sure there are no major cracks or depressions in the floor — fill these as previously described.

Nail a batten temporarily across the threshold of any interconnecting doorway to provide a positive edge to the screed. When it has set, remove the batten and trowel a narrow sloping fillet of mortar along the edge to blend it into the adjoining floor.

Water-proof membranes may be thick plastic sheet, PVC, butyl rubber or painted-on bitumen emulsion, and to be effective they must provide a continuous layer across the floor and be joined to the wall flashing.

If the waterproof membrane becomes punctured, damp patches will appear on the floor- covering. Small areas of damp can be treated by breaking through the surface screed and coating the damaged area of waterproof membrane with bitumen emulsion, then rescreeding with mortar.

If the problem is widespread, or if the floor has no waterproof membrane at all, the real solution is to dig it all up and lay a new floor.

You may find that a problem floor is simply due to one or two joists having become twisted and this can be cured by toe-nailing tight fitting wooden struts between them. However, if the wood is being eaten away by insects or rot, you will have no option but to replace every affected piece.

Lever up a sufficient number of floorboards to get at the affected joists, using a claw-headed hammer with a wooden batten to help leverage. Pull out all the nails and stack the boards so that you can replace them in the same order.

If only a small section of a joist is damaged, the affected area can easily be sawn out and replaced. However, for safety, make sure that the cuts are at least 24in beyond the damage.

Removal of a complete joist will mean levering it from its wall plates at each end, and also any intermediate wall plates. If the ends are set in sockets in the wall, cut through the joist just short of the wall and pull the stubs out. Brick up the sockets, cementing metal hangers into the top joints.

If only a section of joist has been removed, cut a new piece of joist to the same size plus extra wood so that it will overlap the ends by at least 18in. Bolt this to the old joist with two carriage bolts at each end.

If a complete joist is to be fitted, trim back its ends to a taper so that there is no chance of it touching the external walls. Toe-nail the joist to its wall-plates.

If the wall plates themselves are affected, replace them at the same time, simply laying them on top of the sleeper walls. Make sure you prevent contact with the masonry by laying a strip of flexible flashing along the wall first. It is recommended that pressure treated lumber be used for replacement sections.

Something to watch out for are pipe and cable runs below the floor. Pipes are usually set in shallow-cut notches in the tops of the joists and cables pass through holes drilled in them.

Always remove the fuse, or flip the circuit breaker, controlling any underfloor electrical circuit before work begins. Cut the cable out of the old joist by making two saw cuts down to the hole. Make similar cuts in the new joist and glue the offcut back for added protection. Alternatively, disconnect the cable from the nearest fitting and thread it through the holes.

While the upper floors of a house will always be constructed of wood, the ground floor may be made of wood or it may be of solid concrete.

All wood floors are based on the same method of construction with minor differences. They all have a supporting framework of wooden beams called joists onto which are nailed wooden boards or plywood panels and may have a plain or decorative finish.

The joists of wooden ground floors are supported at their end — and sometimes at one or two points in between — or additional wood beams known as “wall plates”. These, in turn rest on the tops of low brick “sleeper” walls.

These are not solid, but are laid in honeycomb fashion with spaces between the bricks to allow the air to circulate below the floor to prevent condensation and rot forming. For the same reason, vents are usually fitted at the base of the external walls and must always be kept clear. Slates or strips of flexible flashing material are laid between the wall plates and sleeper walls to prevent damp attacking the wood.

Sometimes the joists are laid on top of individual bricks set on the ground. Upstairs, the joists are also supported by wall plates but these are held by metal brackets called joist hangers, which are cemented into the walls. Sometimes the joist ends may be set in sockets between the bricks, with a metal plate below to spread the load through the wall.

Most modern houses have solid ground floors. These comprise of a layer of compacted gravel on top of which is a 4in layer of concrete called the subfloor. A damp-proof membrane bitumen or thick plastic is laid next and is carried up and down the wall to link with the flashing around the base of the house.

A thin layer of mortar can be laid on top of the membrane which will provide a level surface for most types of flooring.

Over the years a wooden floor can suffer considerably from wear and tear. The joists may warp or sag, boards may shrink to open up gaps through which draughts whistle, or they may become loose or damaged. The whole structure may be further weakened by woodworm or rot. Fortunately, many of the minor problems can be cured easily, although serious rot or insect attack may mean complete replacement and should be dealt with by a specialist.

Probably the most common fault with a wooden floor is creaking floorboards due to the fixings working loose. The cure is simple: either drive the nails back in or replace them with longer nails or screws. Punch nail heads below the surface and countersink the screw heads.

Gaps of less than 1/tin can be filled with papier-mdché, which you can make yourself. Half fill a bucket with small pieces of torn, soft white paper, gradually adding boiling water while you pound the paper into a thick paste. Allow it to cool and stir in enough cellulose wallpaper paste to make a thick mixture. Add wood stain to match the color of the boards.

When the papier-mâché is quite cold, force it between the boards with a filling knife, leaving it slightly proud of the surface. Leave it for at least 48 hours then sand smooth.

Fill wider gaps with softwood fillets: cut the fillets fractionally wider than the gaps they are to fill, using a backsaw. The fillets should be fractionally deeper than the floorboards: that is, about lin. Plane the fillets so that they taper slightly at the bottom then tap them into the gaps with a hammer and block of wood. Use a plane to shave the top edges of the fillets flush with the tops of the floorboards. Make sure the ends of fillets meet on a joist: secure them to the joists with brads.

Damaged boards

Damaged sections of boards should be cut out and replaced, or a new board fitted if the damage is substantial. First check that there are no pipes or cables running below the damaged section, otherwise you will have to remove the entire board in case you cut into them by accident.

To cut out a section of board, first find the edges of the joists at each end. Do this by sliding a knife blade along the gap between the boards. If the boards are tongued-and-grooved, you will have to cut through the tongues by drilling a starting hole and using a keyhole saw or with a circular saw set to the depth of the board.

Drill a starting hole for the saw just in from the edge of each joist and cut through the board at each end in line with the joist edges.

Lift out the damaged section; if it is nailed to intermediate joists, lever it free using a masonry chisel and a stout length of wood. Lever the board upwards at the fixings with a chisel until you have lifted the end enough to be able to slide the wood below it, while resting it on the tops of the boards on each side. Pushing down on the end of the board will spring the fixings from the joist. Continue in this fashion until you have freed the board. A complete floorboard can be removed in the same way.

Screw or nail lengths of 2in sq batten to the sides of the joists flush with the undersides of the old boards. Then nail a new section of floorboard to the tops of the battens.

Sagging joists

On wide, unsupported spans, the joists may sag in the centre of the floor, giving it a slightly “dished” surface. To overcome this, add packing pieces to the tops of the affected joists.

Lift the floorboards and place a straightedge across the joists at several points. Measure any gap between the tops of the joints and the straightedge and use the measurements to mark out lengths of softwood batten. These must be the same width as the joists. Plane the battens to size and nail them to the tops of the affected joists. Finally, re-lay the floorboards.

Having set the new lintel in place and re-finished the brickwork of the inner leaf above it, you can cut out the brickwork at the sides of the opening and, if necessary, across the base. First, draw the outline of the new opening on both sides of the wall, making it about lin wider and deeper than the actual frame dimensions to give a fitting tolerance.

External walls comprise two layers of bricks; each layer should be treated separately, working in from each side of the wall.

If the wall is a solid one produce a square edge along the opening outline on the inner layer by cutting through bricks where necessary. Always remove complete bricks even if they project beyond the outline. This gives a toothed effect to the edge.

If the base outline runs through the center of a course of bricks, remove the course completely; you can make up the difference later.

Replace the outer layer at the sides of the opening by mortaring cut bricks into the toothed sections so that their cut ends are innermost.

Next, replace the area of wall above the window, laying the bricks on the lintel and copying the original brickwork bond for strength and appearance. In a solid wall, you can create a curved, self-supporting soldier arch by setting a wooden framework in the opening on which the bricks of the arch are laid. Then the surrounding courses are fitted round the arch and the mortar left to set for a couple of days before removal of the formwork.

The frame must sit squarely in the opening; if it is twisted, you may have problems in opening and closing the window and the glass will be under stress and may shatter at the slightest vibration.

In a solid wall you can set the frame: flush with the outer face with its sill overhanging the edge; in the center of the opening with narrow reveals on each side; or flush with the inner face with a sub-sill at the bottom to throw water clear of the wall.

When the frame is set forward in the opening, the sides and top of the reveal are plastered and a wooden or tiled window board set across the bottom. When set at the back, it is normal to trim around the inside of the frame with molding

The simplest method of securing the frame is with frame fixings, a hefty screw and long plastic wall plug, but you can also use conventional wallplugs and screws, wooden wedges or metal frame ties. With each type, wedge the frame in the opening with wood offcuts so that it is set squarely in place, while the fixings are marked and made.

With screws and plugs, clearance holes must first be drilled in the frame and the hole positions on the wall marked through these. The holes are drilled and plugged and the frame fitted.

Wooden wedges are tapped into slots cut in the mortar joints and the frame nailed to the wedges. Metal frame ties also fit into slots in the joints, being screwed to the frame and mortared in place.

In all cases, you must leave a’/sin gap between the top of the frame and the underside of the lintel to allow for any settlement of the structure.

Leave the packing pieces in place. and fill the gaps at the sides with mortar, leaving it about 1/sin below the level of the frame face. Fill this gap with caulk when the mortar has set. Use caulking to fill the gap between the lintel and frame also. If there is a gap below the frame, fill this with bricks and mortar, splitting the bricks lengthways if necessary.

Make a sub-sill from wood screwed or nailed in place, or a double layer of tiles set on a sloping bed of mortar.

Another way is to cast a concrete sill in situ, making up a wooden formwork “tray” nailed to the wall. The sill should overlap the edge of the bricks by no more than in and you can form a drip channel (to prevent rainwater trickling under the sill) along the bottom edge by pinning a length of waxed cord (sash window cord will do) in the bottom of_ the tray. The top of the lintel should slope downwards so angle the sides for this. Also provide reinforcement by setting steel rods in holes drilled in the brickwork.

Mix the concrete from 4 parts sand: 1 part cement and pour it into the form. Agitate the mix to compact it and remove air bubbles and draw it off level with the top of the form. Leave the concrete for at least 24 hours before removing the foiinwork.

The frame fixing is much simpler to use and is ideal for securing wooden members to masonry. It comprises a hefty screw and a long plastic wallplug.

To use, wedge the frame in its opening and drill holes for the fixings right through it and into the wall. Without removing the frame, tap the plug and screw combination through the frame and into the wall, finally tightening the screw for a secure fixing.

Frame fixings are supplied in various lengths to hold wood thicknesses up to 33/sin. Another development of this is the hammer fixing, which is used in the same way, but set by driving a ridged, countersunk pin into the expanding plug.

The way you tackle the job of making an opening in a wall or removing the wall completely in your house, depends on the type of wall it is and its construction.

A load-bearing wall contributes to the strength of the house by supporting some of its structure: a floor/ceiling, an upstairs wall or part of the roof.

A non-load-bearing wall is simply a dividing partition and its complete removal will have no effect on the rest of the house.

Inspect the floor space above it for signs that it supports the joists, or an upstairs wall. Look in the attic, too, to see if any of the roof framework rests on the wall in question.

All external walls are load-bearing and in general any wall at right-angles to the joists will be load- bearing too. Walls that run parallel to the joists are probably non-load-bearing.

Walls may be of brick, concrete blocks or be wood framed. All three types of construction are used for both load-bearing and non-load-bearing walls.

When you make an opening in a wall, no matter how narrow or wide, you must insert a supporting beam or lintel across the opening to take the load of the structure above, even if it is a non-load-bearing wall. The problem is that even by removing a narrow row of bricks or blocks to make room for the be will put the structure at risk.

For a narrow opening like a door, the bond in pattern of the bricks or blocks will tend to make the wall above the opening self-supporting (or self-corbelling) and only a small triangular section of masonry will be at risk. This can be removed, the lintel fitted and the masonry replaced.

With a very wide opening, the self supporting tendency will disappear and a wide area of the wall will be liable to collapse. To prevent this happening. you must support the wall (and sometimes the ceiling on either side) temporarily with heavy wood and adjustable props.

Openings in walls may be spanned by lengths of concrete, steel or wood. Those for fitting over small openings like doors and windows are called lintels; those for spanning wider gaps are called beams. The following are common: Steel Joist — a heavy I or L-shaped girder for spanning very wide gaps in load-bearing walls; Reinforced Concrete Lintel — for internal or solid brick external walls in spans of up to 10ft.

Heavy to lift and often cast on the job site, is the Pre-stressed Concrete Lintel — lighter than reinforced concrete lintels but not suitable for load- bearing walls, except in upper floors. For spans of up to loft, the wood lintel is used in wood framed walls.

Plaster is an excellent and inexpensive material for giving a smooth, hard surface to an internal wall so that it is ready for painting or wallpapering.

There are many types of plaster, but they can be divided into two basic types: gypsum-based and cement-based. The former are used solely for indoor work, whereas the latter are mainly used outdoors for rendering walls. Cement- based plasters do have a use indoors. however, and that is to finish external walls that might be subject to damp penetration; damp will attack a gypsum plaster and cause it to crumble.

Modern plasters come premixed with lightweight fillers such as perlite or vermiculite, which give a higher degree of thermal insulation and fire resistance and should be mixed with clean water.

Plaster is normally applied to the wall in two layers. The first, called a “floating” coat, is intended to even out the irregularities in the wall surface, so it is kept fairly thick — about 3/sin being usual. The second, finishing coat is spread much thinner Ysin or so — and carefully toweled off to a smooth finish.

Different types of building materials absorb water at different rates and if too much water is absorbed from the fresh plaster, it will dry too quickly and crack.

For example, bricks and lightweight building blocks absorb water quickly and are termed high suction surfaces. On the other hand, materials such as concrete and gypsum board do not absorb water that quickly and are termed low suction. You must choose a plaster to match the surface; but if in doubt, the best thing to do is coat the entire wall with a bonding agent which will make a low suction surface.

Browning plaster should be used for the floating coat on high suction surfaces and Bonding plaster on low suction surfaces. Finish plaster can be used for the finishing coat in both cases.

Only buy plaster as you need it since it has a limited shelf life. A 22lb bag of Browning or Bonding plaster should cover an area of about 1.8yd2 at a depth of 3/sin. The same quantity of Finish plaster, spread thinly, should cover an area about 6yd2.

In addition to a couple of clean buckets and a long level, you will need some special plastering tools: a spot board about 3ft square and supported on trestles or an old table to hold the mixed plaster while you work; a hawk for carrying small quantities of plaster to the wall; a rectangular metal plasterer’s trowel: a wooden float for producing flat surfaces (with a few nails knocked into the end it can double as a “scratcher” for scoring the floating coat before applying the finishing coat): and a 5ft length of 1 x 3in planed wood for leveling the plaster surface.

Cleanliness is essential when mixing plaster. since any dirt present in the mix will affect the drying time. Always use clean tap water for mixing and have a separate bucket of water for cleaning the tools as you work.

Mix the plaster and water in equal volumes in a clean bucket, adding the plaster to the water by sprinkling it on top and breaking up any lumps between your fingers. When the water has soaked into all the plaster, use a thick piece of wood to stir the plaster into a smooth consistency, (Finish plaster should resemble runny ice-cream). and make sure there are no lumps.

Wet the spot board and turn out the plaster on to it, kneading it with the trowel. If the mix appears too wet, sprinkle on a little more plaster and mix in with the trowel.