Gaz Bancroft Posted December 19, 2023 Share Posted December 19, 2023 I have planning consent in place for the attached and I am currently tendering to main contractors with a view to commencing build in the summer. I have specified attic trusses as while my budget will not allow currently allow, and I do not need the space currently, I would like the ability in future to convert the loft space to provide two additional bedrooms. I have also specified that the trusses by spaced such that there is sufficient space between them to allow a new set of stairs to be installed above the stairs that run from ground floor to first floor. A builder has suggested that the rest of the trusses will be spaced 600mm apart and so it would be easy to install say 4 velux windows between the trusses on the north facing roof. What angle roof trusses should I specify to provide sufficient headroom? I presume I need the headroom up there to be something like 2.1 metres at the tallest bit in the centre? Many thanks for any other input and advice on how to future proof for an easy later conversion. 23-131b (16).pdf 1 Link to comment Share on other sites More sharing options...
markc Posted December 19, 2023 Share Posted December 19, 2023 The trusses would be 600mm spacing and trimmers are added around an opening for stairs etc. roof pitch will be determined by the design and max ridge heights etc. a truss supplier will be able to design accordingly. Link to comment Share on other sites More sharing options...
kandgmitchell Posted December 19, 2023 Share Posted December 19, 2023 Make sure that you have at least 2.0m headroom where the new stairs arrive on the second floor for an area = width of stairs x width of stairs Link to comment Share on other sites More sharing options...
cwr Posted December 19, 2023 Share Posted December 19, 2023 I'm in the middle of converting my attic having recently moved in and having had pretty much the same plans as yourself. My trusses were at 400mm centre having given no thought to roof windows, would have made life easier if I had at least looked up the standard widths and space a couple to suit. Get in double trusses too where they will be needed. Watch for min max height of the lower openings if they are to be escape windows and also the distance down the roof the the eves, think its 1700mm max. Check head room on landing at top of stairs if it's under the sloping ceiling. Where are the stairs going, make sure they are drawn up to ensure they fit etc. I had our sparks run a pair of wires up for a ring for sockets, and supply for lighting. MVHR ducts, rad pipes, smoke alarm wiring also all worth considering if you meed any of them. Link to comment Share on other sites More sharing options...
cwr Posted December 19, 2023 Share Posted December 19, 2023 Oh, and read up on your local regs in relation to protecting against spread of fire. May complicate things and impact door spec on the other floors. 1 Link to comment Share on other sites More sharing options...
ProDave Posted December 19, 2023 Share Posted December 19, 2023 Re roof pitch. 45 degrees any day. It just makes everything so much easier. Only consider something less if you have a strict planning height restriction. Link to comment Share on other sites More sharing options...
ETC Posted December 20, 2023 Share Posted December 20, 2023 11 hours ago, cwr said: Oh, and read up on your local regs in relation to protecting against spread of fire. May complicate things and impact door spec on the other floors. Becomes a three-storey dwelling. Protected stairway and fire doors required. Link to comment Share on other sites More sharing options...
kandgmitchell Posted December 20, 2023 Share Posted December 20, 2023 8 hours ago, ETC said: Becomes a three-storey dwelling. Protected stairway and fire doors required. Yup, extra expense to consider at this stage as presumably you wouldn't want to throw the doors you fit to a 2 storey house away when you convert the loft. I'd say fit them now as it means the means of escape windows on the first floor aren't strictly needed as you'll have a protected stairway (but still nice to have). The days of allowing means of escape via windows from the second floor have gone. Can you imagine hanging by your fingertips, laying on the roof tiles with feet in the gutter waiting for a fire engine to come and get you out of the smoke with flames licking around your toes ....Just think of your kids or your granny! Link to comment Share on other sites More sharing options...
DevilDamo Posted December 28, 2023 Share Posted December 28, 2023 On 20/12/2023 at 17:21, kandgmitchell said: Can you imagine hanging by your fingertips, But the regulation wasn’t there for that purpose, but for the fire brigade to put a ladder up to that specific window. Link to comment Share on other sites More sharing options...
Gaz Bancroft Posted December 28, 2023 Author Share Posted December 28, 2023 Thank you all for the advice. So, I have specified 40 degree attic roof trusses at 600mm centres. This means I should be able to pop 4 x 600mm velux windows in at a later date and I have specified double trusses around a gap wide enough to install stairs and I have designed space on the first floor landing for where the stairs will go. 40 degree trusses should give me about 2.1m headroom above where the stairs emerge. Have also specified a lighting circuit as will be handy to have a light up there even before I convert as will use as loft storage space to begin with and have also specified a double plug socket at either end of the loft space so will be easy to wire additional plugs off this circuit in future. Will take a look into specifying fire doors to provide a protected stairway, hadn't thought of that so much appreciated. I think I should then be all set for a relatively simple future conversion if I ever need the space or will do prior to selling to maximise value, can turn my new build from a 3 bed to a 5 bed so I imagine the cost of the conversion will be less than the uplift in value. Thanks again Link to comment Share on other sites More sharing options...
DevilDamo Posted December 28, 2023 Share Posted December 28, 2023 You can trim out trusses to accommodate wider rooflights, so don’t think you’re limited to 600mm wide units. I assume you’ll be insulating at rafter level then? Link to comment Share on other sites More sharing options...
kandgmitchell Posted December 30, 2023 Share Posted December 30, 2023 On 28/12/2023 at 10:12, DevilDamo said: But the regulation wasn’t there for that purpose, but for the fire brigade to put a ladder up to that specific window. Well it was for ladder rescue, not necessarily by the fire brigade. Siting at max 1.7m up the roof slope would almost certainly involve some access onto the roof slope to reach a ladder set against the original house eaves. I was perhaps over stating the "toes in the gutter" for dramatic effect, but I would still not like to be getting out that way rather than rely on a protected stairway! Link to comment Share on other sites More sharing options...
Gaz Bancroft Posted January 2 Author Share Posted January 2 On 28/12/2023 at 11:43, DevilDamo said: I assume you’ll be insulating at rafter level then? Yes as part of a future conversion I will insulate and plasterboard when installing the windows in the roof. Noted re trimming roof trusses for larger windows but I think it will be fine with two 600mm wide windows in each room, four in total as I intend to split the space in two to create two extra bedrooms up there Link to comment Share on other sites More sharing options...
DevilDamo Posted January 2 Share Posted January 2 The drawing will need to be amended to indicate and specify the insulation to be at rafter and not ceiling level. Link to comment Share on other sites More sharing options...
ETC Posted January 2 Share Posted January 2 1 hour ago, DevilDamo said: The drawing will need to be amended to indicate and specify the insulation to be at rafter and not ceiling level. I think that’s the least of his problems. 1 Link to comment Share on other sites More sharing options...
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