Loft Conversion

DIpY Loft Conversion*
(*Do It Partly Yourself!)

Gable Wall
Having got the floor done (and had the BCO give it the thumbs up), the next job is to set about the hipped roof and turn it into a gable end wall. Alas this is not quite as simple as pushing it up straight! The first rather dull job is to remove and stack all the tiles from that bit of the roof, strip off the old sarking and all the tile battens, and finally de-nail all the rafters (we will reuse the timber for the stud work in the gable wall). Then at last we can get a bit chop happy ;-) Removing tiles is actually simple enough with two people. One sits on the top of the roof, picks up each tile in turn, flips it over and lets it slide down the roof. Someone at the eves grabs them and stacks them.	Here we see Trevor romping up the slope of the roof (now sans tiles) as he is inclined to do with little provocation, just prior to an aggressive pruning of all those nice rafters with the beast! (and yes, that was quite good fun!).
Having got the rafters cut away from the hipped roof it is time to start building the gable end. This is actually a reasonable quick process. We start by making a copy of one of the existing front rafters to use as a pattern, then all of the required new rafters are produced quickly just by copying the pattern. The first two rafters at the gable end are inserted - nailed to the supporting walls at their "birds mouth" joint, initially just resting on each other at the apex of the roof line. Next the extension to the ridge beam can be inserted. Since access to the existing ridge is restricted by other rafters and the original hip beams this is just tack nailed until a better joint can be made later. The wall in then built up from studs at 400mm centres with another beam inserted at the top, level with the underside of the edge rafters. Ultimately this will be the the beam to which the outriggers can be fixed that will support the fascia/barge boards to the edge of the roof.
The outside of the wall is then felted with "under tile felt" (i.e. the hessian reinforced stuff). This is just tacked into place with a few galvanised nails bent over at the ends. Next 6mm thick battens (made by ripping strips of the side of a sheet of ply) are nailed down over the felt in line with each stud. Finally EXPAMET mesh is then carefully air stapled over the whole surface ready for rendering.	The battens help lift the mesh from the surface every so often so as to make a better key for the render. In addition to helping key the render to the wall, the mesh should end up bonded into the render giving reinforcement which will help prevent cracking.
This is an internal shot of the wall. It took about half a day to build the studwork. Note also that we reused much of the timber from the rafters we cut away from the original roof. The cladding is 19mm WBP shuttering ply. This was tacked in place with an air nailer using 50mm 18g brads before being screwed down to all the studs with a couple of hundred 2" screws! (the plans only called for 1/2" ply here, but I thought we may as well push the boat out in the interests of a bit more strength and noise insulation).	By offsetting the position of the ply sheets such that they do not ever all end on one stud, we help increase the rigidity of the wall by virtue of the ply helping to tie the studs together.
Finishing the Front Having got the gable wall in place the next priority is to get the front roof section completed since it is not dependant on any other parts of the build. Once this is done it can be felted and have the tile battens nailed on after which it should be reasonably watertight even without the tiles.
One of the key requirements for the front roof section is the construction of the dwarf wall under it. This serves several purposes. Firstly it will support the weight of the roof (taking the place of the main roof purlin that need to remove). It will also provide a suitable "end" to the room (rather than have it tail off to a point in the eves), and finally it will eventually have some access doors inserted so as to reach the remaining loft space that is now behind this wall.	The dwarf wall still in its studwork phase. Note also that the new rafters have been inserted (but not yet fixed in place) and some of the older ones that were not long enough to reach the new ridge beam (or get in the way of the roof window) have been cut off.
TaDa! First window in place. The second window will be inserted much higher than this toward the other end of the room, so as to spread the light about a bit. We have elected to use two windows of the same size and type even though there is no requirement for a second means of escape window. The top opening design also means that us taller folks will be able to stand upright in the second window when it is open and look out!	Due to building / fire regulations there must be a "Means Of Escape" window in each habitable space, and it must not be more than 1.7m from the eves of the roof. This does limit how high the bottom sill of the window can be (only 2' with the shallowish pitch of our roof), it also means that our dwarf wall needs to "step in" toward the front of the house so as to not cut off the bottom of the window.
For the first time in a week the weather has been good enough to take the covers right off the front of the roof! This makes progress much quicker. We are also now on the reconstruction phase of the front roof. The whole lot has been felted and battened so should at last be water proof (so I can play fewer games of "find the leak and stick a bucket under it!") The tiles which were so easy to remove and stack, now need to be placed back into position. Needless to say this is a far slower job!	Another day on the front should complete it including the flashings for the roof windows.
The Rear Dormer Having got the front mostly done (except for a few tiles at the ridge and the eves) we can now turn our attention to the rear dormer. This is the last major bit of structural work that we need to do. The design here is a little unusual. Traditionally when you add a large rear dormer you would need to insert a large beam under the ridge of the roof to support the weight of the front tiled section (since you will be taking away the matching rear roof section that has until now balanced the front section and kept it in place. However, this conversion has a partition wall not far from the centre of the house, which can instead be made load bearing. Since it is not directly under the ridge it instead holds one end of the roof joists for the dormer - these in turn run over the partition wall and meet the ridge where they can act in cantilever to support the ridge. To construct the dormer we need to erect some of the partition wall studwork, and also the rear "goalposts" which carry the other end of the roof joists.
The partition wall is partly built, and holes knocked through the existing roof to allow its top rail to poke through and run across the outside of the roof. The goalposts at the rear of the house are also erected so that the roof joists can now be installed. After the roof joists come the firings (i.e. tapered bits of wood to provide the required fall over the span of the roof so that it drains correctly). We ripped these down with a circular saw from some spare 6"x2" roof joists timbers. Once the joists and firings are placed over the span, and are correctly spaced out and fixed, we can throw some sheets of ply over the top and cover with plastic sheeting to keep us water tight. (Needless to say this requires the manhandling of a further 9 sheets of 18mm WBP shuttering ply up the ladder, and then onto the roof - next time I will specify the addition of a winch to the scaffold!)	What will become the wall that divides the two main rooms. The goalposts are visible in the background while the structure of the remaining section of what was the rear roof is now all "inside" the envelope of the new roof.
	The new roof joists have their ends cut at an angle matching the front roof slope, these are then run right past the ridge such that they end next to the front roof rafters. These are then bolted firmly together (with a spiked timber jointing "dog" between the wooden bits)
The remaining task is to now get shot of the old roof. Old roof, please meet the beast ;-)	That was fun! At a stroke we have now doubled the amount of usable floor space in the loft. We can also reuse the old rafters to fill in the missing studs.
Niff Naff One of the usual observations about running any large project is true of this one. That being, that doing 90% of the work takes 90% of the time. Doing the remaining 10% of the work takes the other 90% of the time! Building the entire supporting floor structure only took six days, some other "little" jobs seem to take as long or longer!
One such job is a result of a comment made on the plans by the BCO - that if the plasterboard thickness to the first floor ceiling was not 12.5mm, then one should use rockwool suspended on chicken wire to improve the fire resistance of the new floor. By the time you have got a roll of chicken wire and cut it in half, then proceeded to unwind the irritatingly twangy 100M of stuff and stick it between all the joists, then staple it in place, and finally overlay it with that vile creation rockwool (or Isowool as we actually used) you have spent an awful lot of itchy scratchy days doing it!.	Grrrr!
Walls Now that the main "envelope" of the structure is in place we can start filling in the walls. This is a two stage process. The first is the cladding of the exterior of the dormer (the exterior walls being finished in the same way as the gable end with a felt and Expemet layer on top prior to rendering). The second is the building of the internal studwork that will later form the dividing walls.
A view of some of the internal walls. Here is the bathroom side wall and the stairwell.