Is a loft extension possible in my house ?

EachPenny

Homeadvice wrote: »

So it sounds that the beams can be moved the entire loft is around 6m x 10m so a lot of space to be gained.

I think you might be being a bit optimistic there. The pictures are a bit dark so it is difficult to tell for sure, but it looks like you have Fink Trusses (or possibly 'Double W'). See here for an example:-
https://www.localarchitectsdirect.co.uk/sites/www.localarchitectsdirect.co.uk/files/Trusses%20image%201.png

With those you should* be able to use the area within the central triangle (i.e. between the two tension webs) without any problem, but your pictures suggest the angle of that central triangle is quite acute, so the available width at floor level is quite small. If that distance is 6m then your camera is taking very distorted pictures.

I say 'should' because the other factor will be supporting the load of the floor. The bottom chord of trusses is generally designed only as a tension member to resist spread of the rafters, and to support the weight of the ceiling below. You are likely to need additional structure to take floor loadings, and that structure will need to be supported on walls below. If your internal walls are non-loadbearing then that could be quite a challenge.

Trusses are usually designed to produce an optimal loadbearing capacity with the least amount of timber, so they often have minimal spare capacity for additional loads. It also means that moving individual parts of the truss (for example to make more floorspace in the middle) might not be possible without increasing the CSA of other members. That might involve doubling up the rafters, for example. Trusses are also designed and manufactured to work as a single entity, and are not easy to modify in-situ.

So if your trussed roof allows you to have a significant additional foor area without very significant structural alterations then you will be very fortunate indeed. You really need the advice of a structural engineer before going too far with your plans.

Davesnave

I'd just add that someone ought to have laid your loft insulation better than they did! Or perhaps it was fine, until someone else went up there to do another job, like wiring.

onomatopoeia99

Homeadvice wrote: »

I live in Hertfordshire / North London

Then you'll be competing with all the loaded people in Harpenden (it's the schools and the direct line to St Pancras) who are all having their houses knocked down and rebuilt twice the size, so keeping all the builders busy!

VfM4meplse

Just a thought that the good folk on this thread may be able to answer: is planning permission required to raise a roof pitch?

Furts

Homeadvice wrote: »

This is all really promising thank you for the update.

So it sounds that the beams can be moved the entire loft is around 6m x 10m so a lot of space to be gained .

Does anyone know a guide price based on previous experience. I live in Hertfordshire / North London and would be looking to have the entire 6m x 10m converted into bedroom ensuite and storage along the side in the low part of the roof.

Also the staircase would need to be built to provide access.

All in what would be a rough idea on price for this & time frame

We would also like to extend to the rear 2 stories. Is it likely that it would be cheaper to get this done all together by the same provider?

Thank you so much for the great answers really helpful.

I am with Each Penny. You have a trussed rafter roof and these cannot be modified. These trusses are pre fabricated and built down to minimal costs. Indeed your timbers appear undersized by general perspective. Even inserting Velux is an issue with these roofs. OK if a narrow Velux (which are awful) and bracing is not cut, but otherwise a "no".

All this means any conversion becomes a significant challenge. In turn a common outcome is much as the wise Doozergirl has said. In essence remove the roof, which means scaffolding over and weather sheeting first. Then get a new roof in attic truss format, or get a cut roof put in. This costs significant money!

Doozergirl

V4M4meplse: It depends. You can’t raise the *ridge* under PD but you can make changes to pitch.

You can raise a hipped roof to a gable and you can put in dormers that effectively square off the entire roof as long as they don’t overhang the eaves or pop above the ridge line. Would look like a right dog’s dinner, though

Doozergirl

I’m having trouble editing again this morning. By PD I mean Permitted Development Rights, as long as the house hasn’t had them removed for any reason.

Homeadvice

We did have someone in recently to run some cables and so think that may have been the case.

We are considering having it boarded first of all which would be used for storage for the next 10 year as we have NHBC guarantee and so would be unable to make alterations for this period I believe.

I understand your comments with regards to pre fab roof they are actually building the same style of house at the rear of the garden and can see the roofs being brought on site at the moment.

Homeadvice

Furts are you in the trade or had this work done before ?

Do you know roughly the cost to remove a trussed roof and install atic truss?

Kind regards

Furts

Homeadvice wrote: »

We did have someone in recently to run some cables and so think that may have been the case.

We are considering having it boarded first of all which would be used for storage for the next 10 year as we have NHBC guarantee and so would be unable to make alterations for this period I believe.

I understand your comments with regards to pre fab roof they are actually building the same style of house at the rear of the garden and can see the roofs being brought on site at the moment.

Your roof is not designed for "storage". Which means you have to be careful about loadings onto your ceiling timbers. Further, if you board out then you have to be careful about membranes, insulation, cables, services and ventilation. All this is fine if you know what you are doing.

But equally, all this is a potential nightmare with a new home with a 10 year guarantee. You should not really be doing all this, which means if any problems arise expect little help from the builder or NHBC.