Cheapest way to extend?

[Tigercubrider]

a mate at work isn't exactly wealthy and has an ex council terraced house.
He would like to extend out the back. Possibly two stories, more likely one

He would like to remove the back wall of the kitchen (presumably adding a steel)
And have bifold/trifold doors as the new rear wall on the extension

Is a concrete base with brick and block the cheapest way to build?
Or does a sips system work ?

To save money, he thought that getting it to a weatherproof state and waiting to do the internal finishes - a good idea? Or more expensive in the long run?

 

[Notch7]

I suppose it depends on whether he has any building experience.

Brick and block is probably cheapest.

He needs to do his research on foundation requirements, ask neighbours about depths, check trees and hedge distances, check foul drainage, soakaways. All these can add lots of extra money, so best to learn as much as possible before spending money and then learning there will be extra over costs.

 

[^woody^]

He can forget SIPS unless he wins some in a competition.

I'm not sure what your idea of a concrete base with brick and block is. That sounds like a shed.

He will struggle with planning permission for a two storey extension on a terrace.

He will need to allow £30-£40k for a shell and no problems in the ground, and no knock-through, and probably no kitchen or bathroom or carpet.

He has little funds but wants to spend a tenth of the cost on a set of bi-folds?

 

[pilsbury]

Price pretty much depend on whether he is doing it himself or paying a builder to do. A building is a building. Foundations, drains, walls roof, plumbing, electrics. Only a small percentage can be saved on this. All needs to be done. Woody stated £30-40k for a builder to do. A DIY effort will be £10-15k.

Bifold doors are not in the cheap bracket. We opted for 2 sets of 6’ French doors due to this. £1k as opposed to £3.5k.

I also looked at SIPS as my building skills are non existent. Basically told unless you’re doing a huge project or full house build, it will work out more expensive. The measuring, cad design, set up, delivery costs remain whether it’s a small extension or a big job. Brick and block or rendered block is the cheapest option.

 

[Notch7]

If a fair bit can be done by himself and trades are brought in as required to do a specific task, ie blockwork and brickwork to dpc, walls to plate height etc then a lot can be saved.

Those tasks that can be done by himself will save cost and the builders profit margin on materials and labour will be saved.

However in contrast to that, an experienced builder will know how to get things done in the right order, organise scheduling, have loyal subbies and he will know how to do the work correctly. A homeowner without knowledge can get things wrong and any savings are quickly lost by correcting mistakes. Even doing things in the wrong order can waste a lot of time and money.

I would say unless your mate eithers knows plenty or has a good mate as a builder, he might be better waiting and saving up.