timber frame barn conversion. stick build or SIPs?

[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 and 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 a no brainer, 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.

 

Are there other viable build options I've missed? Or is the stick built/ warranty issue not really a problem?

 

Thanks!