uying/mortgaging/selling a traditional terraced brick house with timber-frame rear house extension

mkext

Hello MSE

I was wondering if anyone here has had any experience with buying/mortgaging/selling traditional brick houses with timber-frame rear house extensions?

Background:
I'm in process of planning to build a two-storey rear house extension to an old brick two-storey terraced house (UK, built approx 1890) and I have a few questions. Planning permission is approved, parity wall surveyor has been done and the structural engineer is working on the design and we are trying to decide between a timber frame and traditional brick extension designs.

The reason a timber frame extension is being considered is because a brick one would require a very deep foundation to the basement level, which would be extremely difficult/expensive to excavate. On the contrary, timber frame is lighter so the structural engineer believes it will be more practical and cheaper to build. The outside walls would have a stone render finish so visually it should look like a normal brick house. There is also the option of using bore piles for the foundation, but I understand it is also quite expensive / logistically complex.

I've heard that he UK property market is still very conservative and mortgage companies still shy away from anything other than "standard construction " so it might be harder to sell or have a lower value than a brick house. Important distinction here is that my extension would be signed off by the current building regulations, so in theory, it would not be affected by the problems which gave timber-frame extensions in the UK a bad name a few decades ago.

I want to be able to sell the house within a couple of years (not immediately)

My questions:

1. Is having a "hybrid" half-brick half-timber frame house really going to be an issue for different mortgage vendors and insurers and hence be a problem for the potential buyers (my mortgage provider said they were happy with my plans to build a timber-framed extension and agreed to lend me the money for this project)

2. Am I likely to struggle to sell it for the price of an equivalent brick house even though it is built to the current/latest building regulations? if so, how much could i expect to lose in value comparing to the same sized brick house?

3. Are there any specific considerations when it comes to selling a house like that? Would it be more pragmatic to pay more for the bore piles foundation and build a brick extension? (subject to approx cost being recovered when the house goes on sale)

4. Any other info I should be aware of?

Thank you for reading - any advice would be greatly appreciated!