Indy Total Construction

Your lighting and power accessories will almost certainly need new circuits, which mean having sufficient spare fuseways or breakers at the electric panel, or extending the existing service panel. If you intend extending your central heating system, check that the boiler has the extra capacity.

In general, you will probably have to re-route pipes and cables already in the attic.

Attic conversion work should not be undertaken lightly since major structural alterations to the roof are inevitable. That is why it is essential to employ professionals to carry out at least all the initial design work, loading calculations and the necessary structural alterations. Then, if you want to save money, do the less critical parts of the job yourself: building the dividing partitions, cladding the floor and ceiling, installing the electrical circuits and pipe work.

If you do intend carrying out these tasks yourself, and you have any doubts at all regarding your ability to do so, then consult an expert in the particular area. In the final analysis, it may save much frustration, time and cost.

What the job involves

The weight of the floor, partition walls and ceiling of an attic conversion can be quite considerable and that is without the loading imposed by the framework for a dormer and, of course, the furnishings added to the completed rooms. So the very first job that is done when converting the loft is to build a supporting structure that will be able to carry this loading and also provide partial support to the roof, if parts of its original framework have been removed.

It is most unlikely that the original attic joists will be capable of providing the necessary extra support. There are two ways in which a strong floor frame can be made: either extra joists of the same size as the originals are fitted between them, or a completely separate structure is built on top of them, being supported directly by the load-bearing walls. Of the two, the latter is preferable, since it will insulate the rooms below from noise and vibration from the rooms above. It will also prevent damage to the ceiling during the construction stage. However, the available headroom will be reduced.

The separate framework will consist of strong wooden beams called trimmers placed around the edges and at strategic points joists will be fitted between them on metal hangers. Where trimmers and joists pass over intermediate loadbearing walls they are packed out with wood blocks for support.

Once this framework is in place, the necessary modifications can be made to the roof itself – adding extra support struts, dormer frameworks and even, in some cases, loadbearing wood-framed partitions.

The floor is normally clad with tongued-andgrooved plywood sheets — a quickly-laid, flat floor.

It is possible to buy standard size flights of stairs, either of the closed or open tread type and, if at all possible, these should be chosen to save on the expense of having stairs specially made to fit. It may be necessary to add a trimmer joist to the floor at the foot of the stairs for extra strength; another trimmer will be needed in the attic floor to support the top. The opening for the new stairs will be quite large and roomy, requiring several original attic joists to be cut through. Their ends must be supported from the new framework with trimmer joists or metal hangers.

The staircase itself may need cladding along the underside with gypsum board, unless it is of the open-tread variety.

Joists for the ceiling can be nailed- between the original rafters, and if a dormer is fitted they are bolted in place and carried through to support the dormer roof.

The internal walls can be lightweight stud partitions. The frames should be nailed together flat on the floor and then lifted into position where they can be nailed to the floor joists, the ceiling joists and to the rafters or other parts of the structure. Always notch the frameworks to fit over the existing roof members, not the other way round otherwise you will weaken the roof.

While the ceiling and partition frameworks are bare, you can fit all the electrical accessory mounting boxes to battens nailed in place and run in all the cables and any pipe work. Then cut insulation material to fit between the studs and bracing of the walls, the joists of the ceiling and the original rafters.

Wall cladding

Clad the walls and ceilings with foil-backed gypsum- board. This will help insulate the rooms and prevent moisture from passing through the walls into the roof space. The final job is to plaster the walls and decorate.

You will need to be able to get to the rest of the roof for repairs and maintenance to water tanks and pipe work, in addition to using it for storage purposes.

To this end, hatches should be built into the partition frameworks. They can be fitted with plywood panels held by magnetic catches and trimmed with molding.

Gypsum board for ceilings comes in two thicknesses: 3/sin and 1/2in, the former being suitable for use where the joist spacing is no more than l8in and the latter where the joists are up to 2ft apart. The standard sheet sizes are 8 and 10 x 4ft. You may find the smaller sheets easier to handle and you can cut them in half to make them even more manageable. The edges should meet on the joist centerlines, so you will probably have to trim them slightly anyway.

The first job is to nail lengths of 2in sq or 2 x Sin wood along the walls parallel with the joists so that its lower edge is level with the undersides of the joists. Then fit more short lengths of wood to the walls between the ends of the joists to provide support for the edges of the boards.

The sheets of gypsum board must be fitted with their long edges at right-angles to the joists. Toe-nail more lengths of batten to act as bracing between the joists so that the inner edges of the sheets will fall on their center lines. A length of batten marked with the board width will help position them accurately.

Finally, mark the position of each joist on the walls as a guide for nailing the sheets in place.

To cut sheets to size, use a utility knife and steel straightedge. Cut down through one face of the board, snap back the waste against a batten and run the knife blade down the crease from the other side.

If you intend plastering the ceiling, fit the gypsum- board gray side down. For painting or papering directly over the top, leave the ivory side showing.

Holding large sheets of board against the ceiling for nailing can be difficult so nail lengths of 2 x lin batten together to foiiu T-shaped props with which a helper can support it while being nailed in place.

Nail the first board in place, working from the center outwards and spacing the nails at 6in intervals. Drive them home so that they just dimple the surface; to be filled later. Use 11/4in gypsum board nails for thinner sheets and 11/2in for thicker kinds.

Continue in this way, working across the ceiling. Keep any cut edges up against the wall, but if this is not possible make sure they meet on a joist with a slight gap in between for filling; stagger the joints.

When you have clad the entire ceiling, seal the joints between the sheets and, if you prefer, apply a thin skim coat of plaster.

The first job is to remove the old floor and dig out the ground below to at least 12in below the final floor level. Lever up an old wooden floor and saw through the joists for easy removal. Then demolish the dwarf walls. Break up a concrete floor: the best way is with a rented jack hammer. Keep the rubble for use as a bed for the concrete later. Wear stout boots, thick gloves, overalls and safety goggles.

Find the flashing in the walls; it may be a layer of slate or bitumen, or one or two courses of engineering bricks. If necessary, chip away the plaster to find it.

If the floor in the next room is of suspended wood, lay plastic drain pipes between any airbricks and the inter-connecting door threshold, setting them in place with bits of stone or brick: this is vital to provide ventilation throughout the floor. Build a retaining wall across the threshold with concrete building blocks.

Next make up some datum pegs from 2 x tin sawn softwood marked with the depths of the bed and concrete subfloor layers: 6in and 4in respectively. Cut a point on one end of the pegs then drive a peg into the ground near a given reference point, to indicate the surface of the floor. Drive the other pegs in at 3ft intervals, checking that their tops are level with the first.

Put down the brick and stone bed, leveling it with the marks on the pegs and compacting it well with a purpose-made tamper. Spread a layer of damp builder’s sand over the top to fill any voids.

The concrete for the subfloor should be of 1 part cement: 21/2 parts concreting sand: 4 parts gravel.

Lay the concrete so that it is level with the tops of the pegs, tamping it down well and drawing a stout batten across the tops of the pegs to level it. Fill any hollows with more concrete then tamp again.

When the concrete has cured, lay the cleavage membrane. With bitumen emulsion apply about three coats, taking it up the wall to the flashing. If plastic sheet is used, tack it to the walls above the flashing. Fold the corners and overlap the sheets by 8 to 12in, sealing the join with building adhesive.

Use 1 x 2in battens to divide the floor into 3ft wide bays for the finishing screed. Set them in place with dabs of mortar, level if necessary by packing offcuts underneath: check with a spirit level.

Fill the bays with a 3:1 mortar mix and draw it off level with a straight-edged batten held across the tops of the dividing battens. When two bays have been completed, lift out the batten in between and fill the resulting slot with mortar. Then trowel both bays smooth with a metal trowel. When the mortar has stiffened, give it a final polish with a wetted trowel.

You need only apply two very thin finishing coats directly over the drywall.

The plaster needed for the job is sold ready mixed or in a powder form requiring only the addition of water. It is mixed in the same way as other plasters and has a creamy texture.

Because you are only applying a finishing coat to the drywall board there is no need for thickness guides, except at any external corners.

It is a good idea to practice scooping the plaster from the hawk on to the trowel first, using a spare piece of drywall to try your hand at spreading the plaster and making it stick to the board_ The technique is to hold the hawk in your left hand (or right if you are left handed) so the top is level and set the trowel blade on edge, so it is at right angles to the top of the hawk. Use the trowel to push some plaster towards the edge of the hawk, scooping it off at the same time as tilting the hawk towards you. The whole is done in one smooth movement.

The first job is to seal the joints between the individual panels of gypsum board, reinforcing them with perforated paper tape or nylon tape to prevent the plaster cracking. The standard paper tape is available in 2in wide rolls of 50-500 feet.

Cut strips of tape to run the length of each joint, including any horizontal ones, before you begin plastering. They must be exactly the right length and should not overlap or be folded, otherwise the plaster will not grip the wall properly.

To seal the joint, spread a thin layer of plaster, about 4in wide, along it from bottom to-top. Hold the trowel so that the blade is at an angle of about 30° to the wall, reducing it as you move up the joint and the plaster on the trowel thins.

While the plaster is still wet, press the tape into it. The easiest way to do this is by draping one end over the blade of the trowel and pressing this into the plaster at the ceiling. Then gently slide the trowel down the plaster, positioning the tape with your other hand. Once the tape is in place, run the trowel carefully up the plaster to make sure it is bedded properly. Treat all the other joints between the panels in the same way.

When the taped joints have dried — which should take about 11/2 hours — fill in the areas between them with more plaster. Work upwards from the floor, spreading the plaster in thin vertical strips and being careful not to build up ridges at the joint positions. Stop just short of the ceiling and work downwards from there to get a clean, sharp angle.

Unless you are working on a very small area, by the time you have finished putting on the first coat, the area you started on will be ready for the second coat. This should be about 1/sin thick and applied with long, sweeping strokes to eliminate ridges. Start at the bottom corner of the wall and work upwards and along to make one continuous coating.

Allow the plaster to set slightly and then go back over it with a clean trowel to smooth off the surface. Finally, when it has hardened fully, “polish” the surface by splashing clean water on to it with a paintbrush (about 4in wide) then sweep the trowel back and forth lightly. This will give a smooth, matt finish ready for decoration.

In converting an attic the installation of one or more dormer windows will not only provide essential natural light but also increase the headroom over areas of floor that were previously unusable.

In addition to providing windows and extra floor space, with a dormer built up from eaves level, you can site a staircase immediately below it fixed to the external wall of the house, whereas normally it would have to run through the center for there to be enough headroom at the top.

Since several rafters will have to be cut through make the doliner, the framework must be strong enough to support the load previously borne by the cut rafters. It must also have support at floor level unless it is possible to set the framing directly on top of a loadbearing wall. The original attic joists would certainly not be strong enough. However, since a dormer will be put in as part of an attic conversion this is not really a problem. A strengthening framework and extra joists will have to be put in for the new attic floor and this can be made to support the claimer framework as well. This new framework is built directly onto the house load- bearing walls and is completely independent of the original attic joists and ceiling below.

Calculating the loads involved and designing the supporting framework is specialist work for an architect, engineer or a contractor.

The construction of the donuer framework would follow on from constructing the floor support structure. Once the dormer is complete, do the rest of the conversion work. Access to the roof will be needed so that bulky materials can be passed through from the outside after removing a few tiles or slates and cutting an opening in the roofing felt. An access tower and roof ladder are essential.

The first job is to build the framework of the dormer, making sure it is secure before cutting through the original rafters and removing them.

The first sections of framework to be erected are the two corner posts for the outer end of the dormer. There is no need to strip off all the roofing within the dormer area for this initial construction work; remove

only small sections of tiles and pass the framework through. In this way the roof can be kept reasonably weathertight for most of the time.

The corner posts stand on the supporting floor joists below and are linked immediately below rafter level by a horizontal beam. Short wooden studs are nailed between the purlin and the supporting floor beam. The purlin has two purposes: to tie the bottoms of the corner posts together and to support the lower ends of the original rafters when they are cut through. All the construction is toe-nailed to fit.

Next, nail a horizontal beam across the tops of the corner posts. The joists for the top of the dormer can then be fitted: nail their outer ends to the top of the header and pass them right through the roof and bolt them to the rafters on each side for stability.

If the roof of the dormer is to be flat, tapered wooden slats, called furring pieces, are nailed to the tops of the joists so that the roof will have a fall to the front for drainage. If the dormer is to have a pitched roof, a ridge board and additional rafters are installed above the joists.

Before removing the roof from within the dormer framework, fit additional trimmer rafters between the corner posts and the roof ridge bar (or hip rafter if the dormer is a wide one on a hipped roof). Cut shallow notches in the sides of the corner posts to take the ends of these trimmers, and nail in place.

To complete the framework, the roofing must be stripped off. Lift the tiles or slates from the battens, cut out the felt and saw through the battens to expose the joists: cut these off flush with the undersides of the dormer joists and level with the inner face of the new supporting purlin.

Nail vertical studs between the trimmer rafters and the joists above to provide support for the side “cheek” cladding of the dormer, spacing them to take account of the width of the cladding sheets so that their edges always fall on the centerline of a stud.

Complete the framework by adding a wooden subframe to support the window itself. This is usually a horizontal beam set between the corner posts and supported below by short studs nailed to the top of the new purlin, and possibly to the sides of the cut rafters as well. The window will be narrower than the distance between the corner posts, so nail additional studs between the horizontal beam and header to support it at the sides.

The roof is covered first and if it is flat, it is decked with exterior grade plywood, butting the sheets together and nailing them to the supporting joists. To provide support for the flashing, slip a narrow strip of board under the roof at the junction with the dormer and nail it to the original rafters. To provide a certain degree of protection until the job is completed, you can add the first two layers of felt at this stage, taking them up under the original roof and leaving overlaps at the sides and front for finishing off.

Next the sides and front of the framework on either side of the window opening can be paneled in: you can use foil-backed gypsum board for the cheeks. Nail it to the outside of the framework with the foil side outei inost to prevent moisture penetration.

Fit lead soakers beneath the tiles on each side of the dormer; it may actually be easier to do this before cladding the sides, since they will slip in from the ends of the courses without the removal of the tiles.

Before finishing off cladding the sides, add flashing to the front of the dormer below the window-opening, taking it over the top of the frame-supporting beam and down over the roof tiles or slates below.

If tiles are to be used for cladding, nail narrow battens horizontally around the dormer (the spacing being dictated by the tile size). If boarding is used, nail the battens on vertically. Overlapping tiles and boards are nailed on in pattern to keep out rainwater.

Fit window frames made from seasoned wood. A gutter is fixed along the front fascia board with a short down-pipe at one end which can be led down the corner of the dormer to discharge its contents over the roof below.

Having clad the outside of the dormer and glazed the window, finish off inside — this can be done at the same time as building the interior of the attic room.

While the framework is still exposed, however, glass fiber or polystyrene insulation can be fixed between the various frame members at the sides and in the roof before they are clad with drywall or whatever internal wall cladding is being used.