Single Storey Extension Self-Build Roof Question?
Question:I am currently considering selfbuilding a small single storey extension, I have done a few construction projects in the past and always like a challenge. I am totally happy with foundations, footings, DPC, DPM, bricking, blocking, lintels etc but the roof daunts me. We want a pitched roof and the projects isnt huge at only 3m square but I would like some very, very basic questions answering. I understand that I need to build the brickwork & blockwork to celing height and build up the gable end at the same angle as the trusses. What fastens the trusses to each other and to the gable end and walls. Also once they are in place, is it some kind of felt first, then tile lats + tiles or is there something in between. If the gables are too long, do people just cut them off to fit the soffits & fascia boards. I dont know the jargon and I dont want to sound like an idiot in some builders merchant when I go to price the bits up !
Answers:
It depends on the type of roof structure you want. For example, you can buy ready made trusses which attach to a wall plate set at eaves height, such are held down with clips which you can buy at any builders merchants and the wall plate itself has restraining straps to stop uplift. The trusses are set at 600mm centres so provide fixing for your ceiling plasterboard they themselves need bracing. The roof is normally covered in a felt and then "slate" laths are fixed at centres commensurate with the type of covering you are using-slate or tiles. The trusses will give you the profile to finish off your gable brick and block and they normally overlap the wall plate and are cut off vertically so that you can fix your fascia to such. However, you have to ensure there is ventilation to the roof, so a plastic perforated channel is fixed to the space between fascia and wall. Really, I don't understand your problem, since you will have to provide drawings for possibly planning and certainly building regulation approval and whoever does these drawings for you will detail what needs to be done. Wouldn't recommend doing it without the foregoing, you could find yourself in deep dodo.
First of all, consult your local authority to establish the requirement for a Building warrant which will almost always be required. Also check the necessity for Planning Permission. Generally domestic extensions (single storey) don't need consent if under 24sqm for a detached house, 20sqm for a terraced property and permission always required if its a flatted property, or within a conservation area or if it is a listed building, and will almost certainly requiure to be behind all road facing building lines. Note that these sizes will also include ALL previous extension or additions allready made to the property (cumulative). If you have no warrant or planning permission it can subsequently cost you hundreds to get a letter of compliance/retrospective consent when you come to sell your home - they will also be able to advise you on current building regulations for trusses etc Depending on the size of roof will depend on the spacing of the trusses, and full wooden truss can be accepted in certain circumstances rather than the full metal seat arrangement that some require. Normally the trusses could be in place and longer than required then trimmed back, but best get in touch with Building Control first.
try here for some advice also
http://www.buildingdesign.co.uk...
Nails and timber straps, cut of excess timber when you have set it up.
Bolt timber plates to the wall.
When the formwork is up use breathable felt and batton out according to the tile size using proper roofing galvanised nails.
A overhang is required to fix the fascia and soffet underside and vent the roof area with a tile vent.
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