Is it possible?

[CotswoldDoItUpper]

I can’t get my head around how to do this or if it’s even possible/feasible. I know I’ll need an SE but thought I’d ask experts on here…

so basics: we’d love to add an extra bedroom/bathroom to our loft. It’s 8mx5m with a 2.25m head height to underside of felt from top of joists. Joists are 70mmx35mm with w-trusses.

Space saving ‘loft’ stairs will come up off centre so will need some sort of dormer to allow the required head height. 
we generally dislike the rectangular large dormer thing you see stuck on houses and wanting to try and avoid this if possible, but do like pitched dormers. Can anyone help? I feel a bit lost and confused by the whole design/aesthetic/building regs mishmash. 
 

[CotswoldDoItUpper]

For what it’s worth, my (very basic!) sketchup ideas…

[CotswoldDoItUpper]

[joe90]

IMO That’s a whole new roof, those “w” trusses can’t really be altered without massive work, the flat roofed dormer will give you much more room but i agree with you will not look as good as the individual ones, then again, can it be seen much and by whom?

i think you’re main problem I’ll be height, with only 2.25m you will loose lots with roof structure and bigger floor joists so may not leave enough head height.

Edited March 9, 2022 by joe90

[JohnMo]

Extend walls up and new roof, or move to something already done.

[Marvin]

39 minutes ago, joe90 said:

IMO That’s a whole new roof, those “w” trusses can’t really be altered without massive work, the flat roofed dormer will give you much more room but i agree with you will not look as good as the individual ones, then again, can it be seen much and by whom?

i think you’re main problem I’ll be height, with only 2.25m you will loose lots with roof structure and bigger floor joists so may not leave enough head height.

Yes. What, about 150mm joists at the loft floor and 170mm insulation and plasterboard at the top?  Not enough height in my opinion. 

 

And to agree with @joe90 the W frames use thiner wood but every piece counts like one of those bridges.  

 

Also, I don't think the dormer roof can be higher than the original roof without planning...

 

Good luck

 

M

[ToughButterCup]

58 minutes ago, CotswoldDoItUpper said:

I can’t get my head around how to do this or if it’s even possible/feasible....

 

Of course its possible. The question is ... at what cost?

 

It might even be feasible. Go onto Cotswold District Council's (I may have the authority wrong)  Planning website, register and then use their advanced search facility to look for applications for projects similar to yours. Crawl all over them, know them inside out, visit them. Doing that makes you less of a target for tooth-sucking professionals. Have half a dozen existing examples of what you want at your fingertips so you can say  -- ....I want it like this ....

 

Please bear in mind we are not experts. Nosey, well-informed, experienced,  hard-bitten, yes. But expert - NO.

 

Looks like fun. Keep us posted (we are nosey) 😏

[ProDave]

I agree with others, completely new roof, nothing worth saving.  That type of roof simply is not built to be room in roof.

 

BR require 2M height at the top of the stairs, You will struggle to achieve that even with a dormer at the existing ridge height if you want decent levels of insulation.

[SuperPav]

You'll struggle to get usable headroom if it's 2.25mm from joists to felt at the moment. The rafters will need to be sistered with 6x2's at a minimum + insulation so you're probably at the depth of a 8x2 as a minimum.

Then from the bottom you'll most likely need to sister the ceiling joists with at least 8x2's for the floor, again losing space.

 

Unless there's a very good reason not to, building the walls up even by 500mm either side will make a massive difference and give you a usable space. Alternatively is there anything stopping you from doing an extension as it may be easier than messing about with the loft?

 

As it seems your in my part of the world, if you need any help in terms of planning, let me know.

[PeterW]

1 hour ago, CotswoldDoItUpper said:

Space saving ‘loft’ stairs will come up off centre so will need some sort of dormer to allow the required head height. 

That will fail building regs - they can serve a single room only and that includes bathrooms so if you put a bedroom / bathroom up there it has to have standard stairs. 
 

1 hour ago, joe90 said:

That’s a whole new roof, those “w” trusses can’t really be altered without massive work, the flat roofed dormer will give you much more room

Agree with this - and by the time you’re doing a new roof you may as well go to an extension as anything below 1.4m height is pretty much unusable so your 8x5 will be much less by the time you have finished. 

[CotswoldDoItUpper]

Thanks all. I’m glad you’ve all instantly see the problems I’ve taken weeks to think about! 
 

Would I be able to double up the timber for the joists to keep them thinner therefore loosing less roof height? Then potentially replace with a sips style warm roof to get rid of all internal structure? 
 

then it’s a case of the cost of that to know if it’s viable. 
 

@PeterW can the bedroom not have an en-suite? 
 

@SuperPav the building (imho) already looks slightly incongruous to our neighbours and when it was built (1983) was objected to on height by the neighbours all of whom still live here! The original 1801 cottage is approx 3m lower ridge height - not sure any additional height would be welcomed! Extension might be the best option, but going to exhaust the roof first!

 

@ToughButterCup hadn’t considered snooping into other planning applications…. Will give that a go now, thanks!

 

@Marvin think we have to have planning anyway? We’re in AONB but not conservation or listed. Thought that AONB was designated land requiring planning for loft conversions. If I’m wrong that’s great news!

[SuperPav]

You'll definitely need planning for the dormers if you're in Cotswold AONB. If you're in the curtilage of a listed cottage, this might be a ballache regardless of which route you go to.

However even in a AONB you have some options under permitted development assuming there's no Article 4 restriction or condition of the original planning.

 

Even if you use the smallest 4x2 rafters with dwarf walls or purlins and tie them at the floor, that's not enough depth for insulation to meet building regs. Quite simply within the current set up you won't get a usable room up there.

 

How much headroom do you have in the room below? If you could lose 200mm off that, and add 200mm to the ridge, you might be able to get something to work even without adding height at the eaves.

 

In either case, the whole roof needs to come off, so stop thinking about working with what's there and just start thinking as to what options you've got that you'd get planning for that would still give you the increase in space you want. You may be able to reuse the tiles, but that's probably it. This is also why an extension may be a better choice. And currently living through the nightmare of having the whole roof removed off a house, I can't emphasise just how much more disruptive that is than an extension.

 

All this also assumes you're in a location where throwing a large sum of money at an extra room is a worthwhile pursuit. Remember also that you're also most likely losing a fair chunk of space from the floor below where the stairs are going to go (unless you have a very un/fortunate layout at the moment).

[CotswoldDoItUpper]

thanks @SuperPav 

it’s a detached house, original 1801 cottage extended by previous owners in 1983. No curtilage or restrictions other then general area regulations. Room below head height is 2280 and 230 above windows so sounds like that’s not worth it. 

were 3 beds atm, adding a 4th would in all likelihood add a further £100-150k ish to the house value. it’s more of a thing about how much we can afford - certainly not anywhere near that!

 

rooms below where stairs would come out would be a landing/large bathroom so a space saving staircase would definitely fit, if not a circular stair but a ‘full size’ staircase might not fit so well.

Edited March 9, 2022 by CotswoldDoItUpper
SPG

[nod]

2 hours ago, joe90 said:

IMO That’s a whole new roof, those “w” trusses can’t really be altered without massive work, the flat roofed dormer will give you much more room but i agree with you will not look as good as the individual ones, then again, can it be seen much and by whom?

i think you’re main problem I’ll be height, with only 2.25m you will loose lots with roof structure and bigger floor joists so may not leave enough head height.

Plus 1

 

it's probably not as expensive as you think to start again with a new roof 

Altering trusses is expensive 

and will give you limited options 

[CotswoldDoItUpper]

Has anyone had experience with a SIPS style roof? Any indication of cost? Replacement joists are about £4000+vat+delivery obv then +instillation+insulation, felt, battens tiles etc. I guess SIPS would be the same additional costs except insulation with lower/quicker (?) instillation costs?

[CotswoldDoItUpper]

Ok so having had a play around, this is one bedroom with an en-suite. Does this confirm to building regs for a space saving staircase? 
 

can anyone make any suggestions for the design? 
 

it will be a new roof, structure TBC, again any advice suggestions or experience welcome! 

[CotswoldDoItUpper]

Meant to say, bedroom gable faces due south.

[Tylers]

I think the regs say the floor of a loft room has to be independent from the ceiling beneath it therefore sister ing floor joists if they support the ceiling is out. Leadtways the bco on my last job said that

[joe90]

6 minutes ago, Tylers said:

I think the regs say the floor of a loft room has to be independent from the ceiling beneath it therefore sister ing floor joists if they support the ceiling is out. Leadtways the bco on my last job said that

Not heard that before and I have worked on loft conversions with sistered joists. Personally I prefer independent joists to avoid noise transference between floors.

[PeterW]

On 09/03/2022 at 19:17, CotswoldDoItUpper said:

Replacement joists are about £4000+vat+delivery

Is that a typo……??? Or do you own a very very large house ..?? Currently paying £26 exc for 4.8m C24 195x45 and for a standard house at 400cc that would still only be £1300. 

 

 

[CotswoldDoItUpper]

@PeterW

 

it’s roughly 5.5m span 8.5m long, and I meant trusses not joists!  Think it might be worth just starting again with the roof structure with some stubbed eaves to get more hight. Got to take half of it off anyway to get the gable sorted.

[ETC]

Don’t forget that since this will now become a three-storey house you will have to consider more onerous fire safety measures which will add to the cost.

[PeterW]

4 hours ago, CotswoldDoItUpper said:

@PeterW

 

it’s roughly 5.5m span 8.5m long, and I meant trusses not joists!  Think it might be worth just starting again with the roof structure with some stubbed eaves to get more hight. Got to take half of it off anyway to get the gable sorted.

That’s even worse … £165 per truss at 600cc …. Who are you getting quotes from ..?! 

[CotswoldDoItUpper]

9 hours ago, PeterW said:

That’s even worse … £165 per truss at 600cc …. Who are you getting quotes from ..?! 

[PeterW]

You’d be quicker and cheaper with a cut roof and a steel at the ridge - those are mental numbers at over £500 a truss !!