Block or timber frame?

[Whyisitsodifficult]

We’re in the process of planning a single storey rear extension. Our architects have recommended we build it with a timber frame to allow for more internal space and it’s quicker to go up. In my head an extension should be made of bricks as surely they’re stronger and thermally more efficient? Has anyone any experience in building an extension with a timber frame? By the way I don’t mean a nice oak framed structure where you can see all the beams!

Timber frame does go up quicker but the lead time is longer on it. So it’s much of a muchness. If you’re looking for something efficient and highly insulated try INSULATED CONCRETE FRAMEWORK (ICF)

I take it you are referring to SIPS ? I think is a decent alternative to block brick but I think it may be difficult to get builders who are happy and experienced working with it. Not much in cost savings but you will save time.

As I said SIPS can save on “build time” but the lead time (where they make it in the factory is longer) so it may not save a whole load of time.

Ok I’ve not heard of ICF or SIPS I shall take a look at both. If it makes any difference the whole thing is going to be clad in larch render. So if I had the framework made up in a factory is it not just a case of the builders putting it together like a jigsaw? Would builders prefer to do the carpentry work on-site themselves? Thanks so far all a bit confusing!

We have a timber frame house and had a timber frame extension put on last year. They started end of August and from first day digging the footings to internally plastered was 4 weeks and 2 days. Was absolutely over the moon. You will need a specialist company and our builders were bloody brilliant so I can't say they would all do it so quick. I also did a self build timber frame previously and we achieved better thermal properties with that than if we'd built in block.

Timber frame doesn't necessarily mean 'made off site'. Our single storey extension is timber frame and all built on site by the builders.

Would it be cheaper to be made off site though? coxwell that’s amazingly quick was yours made on or off site? I don’t suppose your builders are south east are they? babytalk how long did your extension take and why did you choose timber over block if you don’t mind me asking? Our extension is 8m x 6m anyone have an idea of cost?

Our house is of timber frame construction with blocks on the exterior of the frame. It's energy efficient & very warm.

Ours took about 4 months but that was to our rear and side extension plus porch and also our neighbours rear extension as we did it as a joint project extending across the width of both houses 3 metres out.

We paid £1,500 per sq m finished with all windows, doors, plaster, skirting, electrics, heating, installation of utility & shower room, rendered, tiled roof.

Architect recommended timber frame to maximise available space.

I’ve just been reading about Sips they do sound interesting, has anyone used this system?

Hmm I’m more confused now. Getting builders in to quote and getting a lot of shaking of heads regarding a timber frame! Builders saying they prefer the old fashioned way of building in brick! Are timber frames not highly regarded in the building world? I know the wishes of an architect and the practical side of a builder can be poles apart, not sure what to do know! Anyway had this experience? Thanks

It's unusual to use in England and Wales , used a bit more in Scotland. Builders like using what they know , they may have never used SIPS before , I'm guessing it would be a learning curve for them. I would go to a company that build these all the time , it will be easier to get a price.

@Babytalkobsession

it sounds like you have done a very similar extension as to the one I am planning....
Can I ask you a couple of questions?
a) whereabouts in the country do you live? £1,500 pm seems such good value, is that due to your area or the fact you used a timber frame?
b) I'm in a semi-detached with neighbours who are planning to extend at the same time, is there any advantage/disadvantage of working together? (Neither of us have had plans drawn up yet)
Thanks if you have the time to answer it would be very appreciated!

Our extension was done in block and my father in law did his timber framed. When we do the granny flat for my parents I will definitely do timber framed. Footings don't have to be so deep, quicker to build and you essentially have walls made out of insulation. They're warmer and more thermally efficient unless you're prepared to have VERY thick (15 inch) walls. Most lumber yards have 6*2 c24 in massive quantities available, so supplying and building a timber framed building is quicker and cheaper.

Walls in my FIL extension are cement hardboard with render on the outside, 6*2 framed and bolted onto the existing walls with threaded rods. All gaps in the timber frame are filled with 6 inch PIR, with thermal foam. Over that is half inch OSB covering every wall and then 1 inch thermaline plasterboard backed sheets fixed to the frame. So all told the walls are 8 inches thick (1-2 inches less than block walls) and his extension is basically passive.

For the wall that adjoins his neighbours house, it was constructed flat, and rendered then jacked into position so even though there is less than 100mm of space between the properties, it is fully finished.

Also because of the 12mm OSB covering every wall you can screw straight into the wall. Additionally the walls are very flat, which made fitting the kitchen very easy. I'm 100% sold on timber frame.

@fastliving I would suggest block inner skin and cavity for your situation, for two reasons.

Firstly, you've said that you want to extend along the line of junction with your neighbour and form a party wall between the two extensions. This is a great idea and will save on cost! However, you will need to ensure that the wall meets sound insulation regs. That will be easier to achieve with a solid block.

Secondly, I use and specify SIPS and timber frame systems every week. However, they need detailing very carefully, which means the builder has to be very good. Any kind of moisture issue will affect the frame far more than it would a more traditional construction.

Both systems can work really well, but when it comes to ground floor extensions I prefer traditional build.

Thanks for your helpful advice @SurveyorScott !

We’re building a whole SIP house, but are working with an architect, manufacturer and builder who have all worked together before and done many of these builds