barn conversion. SIPs or stick build ?

[mattp22]

Hi, I'm trying to wrap my head around a barn conversion I want to start soon. Stone barn in Scotland, very thick stone walls- structurally ok. Slate roof/ timbers well past their best and i need to raise ridge height for first floor head room, so existing roof & trusses are coming off regardless. I have full PP.

 

To convert i saw 3 routes-

a) drop a SIP kit inside. fast, slim and thermally efficient, but tricky to get 100% correct with existing window openings etc, and adjustment on site is not really possible i believe. circa £60k exc. assembly, but includes most internal walls too.

b) ICF- thermally efficient again, reasonable fast, prices quite high and that's excluding a roof. easier to tweak on site to fit existing walls & openings. circa £68k exc. roof, 1st floor joisting & internal walls.

c) stick built on site with local joiners. takes a longer time, but easy to work with existing structure. Including insulation and trusses significantly cheaper than a or b.

 

So option c) seemed easier, but now I'm reading that stick built would perhaps prevent me getting a 10 year warranty and/or straight forward mortgages? There is a good chance I'll sell within 5 years.

 

The ease and speed of using SIPs is very appealing, but i suspect these benfits will go out the window if i have to adjust the panels on site.

Are there other viable build options I've missed? Is adjusting SIPs even possible? I specifically asked the SIP company to give me oversized (too wide & too high) openings for windows & doors so I can bring them in on site with stud work to suit existing openings, but maybe I'm just opening a can of worms.

 

Thanks!

Edited February 10 by mattp22

[jayc89]

Inner leaf of blockwork and blow EPS beads in the cavity you create?

[Alan Ambrose]

Stick build a non-structural truss inside and wood fibre? EWI if your PP will allow it?

[Russell griffiths]

Do you need a 10 year warranty for a conversion??

 

@scottishjohn sounds like your build. 

[saveasteading]

5 hours ago, mattp22 said:

Are there other viable build options I've missed?

Yes.  the wall has stood there for hundreds of years, so keep it and use it. 

 

Our steading has 3 skinned granite walls. we kept the roof so that is a difference of course.

then inside there is a timber stud construction for insulation and decoration and airtightness. 

Thus you are looking at  a stud construction, not structural.

It works a treat.

 

Normal joinery. perhaps copying what is there, or otherwise, but local joiners can do it.

 

For completeness, We had, and have, 4 sides and a central courtyard, with 3 retained sides, as described, but the 4th side had to be removed and rebuilt as if a new house.  That was stick built. 

 

[saveasteading]

 

 

You can see here at the window reveal, the stone as was and the amount of inner lining. there is clear air and dpm between the two elements.  That loss of room width bothered us at first but there was no option really, and it's fine.

There is heat loss through the stone of course but it is art and heritage in place of ultimate insulation and the BCO agreed it was a good thing.  The rest of the house is fully insulated. 

The Scottish reg's allow pragmatism in conversions.

 

Another factor is that, if you built a structural wall supporting the floor above, then it would need a footing.

 

 

 

 

 

 

 

[mattp22]

thanks for the comments.

I'll do some homework re: warranty required on conversions.

and the visible stone reveals looks great.

cheers

[Gus Potter]

On 10/02/2025 at 13:19, mattp22 said:

Hi, I'm trying to wrap my head around a barn conversion I want to start soon. Stone barn in Scotland, very thick stone walls- structurally ok. Slate roof/ timbers well past their best and i need to raise ridge height for first floor head room, so existing roof & trusses are coming off regardless. I have full PP.

 

To convert i saw 3 routes-

a) drop a SIP kit inside. fast, slim and thermally efficient, but tricky to get 100% correct with existing window openings etc, and adjustment on site is not really possible i believe. circa £60k exc. assembly, but includes most internal walls too.

b) ICF- thermally efficient again, reasonable fast, prices quite high and that's excluding a roof. easier to tweak on site to fit existing walls & openings. circa £68k exc. roof, 1st floor joisting & internal walls.

c) stick built on site with local joiners. takes a longer time, but easy to work with existing structure. Including insulation and trusses significantly cheaper than a or b.

 

So option c) seemed easier, but now I'm reading that stick built would perhaps prevent me getting a 10 year warranty and/or straight forward mortgages? There is a good chance I'll sell within 5 years.

 

The ease and speed of using SIPs is very appealing, but i suspect these benfits will go out the window if i have to adjust the panels on site.

Are there other viable build options I've missed? Is adjusting SIPs even possible? I specifically asked the SIP company to give me oversized (too wide & too high) openings for windows & doors so I can bring them in on site with stud work to suit existing openings, but maybe I'm just opening a can of worms.

 

Thanks!

That's a cracking pad!

 

I've done a few of these over the years, hope this helps a bit.

 

a) SIPS. Too tricky and you invetitably make changes as you uncover and discover more about the old structure as you go. The secret is to have an adaptable / flexible design.

 

b) IFC. My own view.. not suited for this application. The problems will start in the ground and work their way up not just structurally and dimensionally but in terms of insulation, condensation risk, detailing and finding a contractor that can get their head around even some of that.

 

c) Stick building (some can be structural some non structural timber panels) is ideally suited to this. Often you want vaulted areas of roof.. that suits a cut roof with the odd steel. Elsewhere you can use standard prefabricated trusses, can be standard finks or attic trusses.

 

I can't see any problem getting a stick build signed off in Scotland as this is the sort of stuff we do a lot of.

 

@saveasteading knows plenty about this, has hands on practical design experience and a great eye for keeping costs under control.

 

As an aside.. see on your rear elevation there is a slight arch over the two cart doors. This is fascinating.. how does it stay up? Well one way is that you have a good bit of masonry butressing them each side. Have a look at this and appreciate the art. Keep this in mind.. if you mess with this too much you could introduce unwanted cost and movement in the masonry.

 

Keep us posted when you can.