Extension . Cheapest option?

[2020c]

I've been noticing more and more onsite timber frame small extensions get built on the back and sides of houses and it's got me thinking is this the cheapest option or is it for better insulation specs to meet building regs. I've been undecided on what building method for my own extension later in the year or next year.

Either a double skin of block with insulation in the cavity or on site built timber frame. Looking at the price of blocks compared to the timber price for wall plates, 6x2s, structural ply, vapor barrier and exterior breathable membrane, staples, nails, vents, fire stopper, straps and the labor involved for all surely the timber frame will cost more than a double skin of block.

 

[charliegolf]

8x4 125mm thick SIP panel- £90. First one I found. Work it out, see how it looks.

 

[JP_]

Some new houses went up near me a few years ago, built with SIPs. I was very impressed with the speed at which the SIP panels were all erected. But then they still had to brick up next the SIPs. I guess they could have rendered, but they used nice bricks. Makes no sense!

Mu extension is block and rockwall - great insulation, and handy to have solid walls everywhere. Can't imagine living in a wooden framed building really

 

[2020c]

Some new houses went up near me a few years ago, built with SIPs. I was very impressed with the speed at which the SIP panels were all erected. But then they still had to brick up next the SIPs. I guess they could have rendered, but they used nice bricks. Makes no sense!

Mu extension is block and rockwall - great insulation, and handy to have solid walls everywhere. Can't imagine living in a wooden framed building really

Wooden framed buildings are very popular in the US and scandanavion countries however not do much in the UK and Ireland although they are becoming very popular I have noticed. I don't know is this a cost issue or better insulation values to meet the new building regs. For speed in a large house I can see how timber frame from the factory can be quicker but for a small 2 or 3 roomed extension, the block work can be erected in 2-3 days for a 2 and 1 squad. For an on-site built timber frame then block the outer skin, I could see it taking the same length of time of longer and the materials for the timber frame costing more for all I've added above. Maybe I'm wrong but that's is my first thoughts looking at the price of timber and other materials needed for it.

 

[^woody^]

Timber frame and masonry are just different methods of construction, each with potential advantages and disadvantages. Costs are not directly comparable, as it's not just a case of comparing the price of sand with OSB or suchlike.

The main issue with timber frame is that there are fewer people experienced in designing and constructing it (or even living in it), and it's easier for small mistakes to lead to big problems later.

 

[2020c]

Timber frame and masonry are just different methods of construction, each with potential advantages and disadvantages. Costs are not directly comparable, as it's not just a case of comparing the price of sand with OSB or suchlike.

The main issue with timber frame is that there are fewer people experienced in designing and constructing it (or even living in it), and it's easier for small mistakes to lead to big problems later.

Yes I understand this woody and they both have there pros and cons, however cost would also have an impact on which one is decided by the home owners. Just like myself wanting to know the costing for the walls either in timber frame or blocks! Building regs allow both and my next thought is, which is the cheapest method. I can live with both but with a tight budget, I'm wanting the cheapest option. Naturally one would think timber would be cheaper but I'm not to sure now because of all the extras thats needed.

 

[2020c]

8x4 125mm thick SIP panel- £90. First one I found. Work it out, see how it looks.

This is an estimate.

Roughly 34 blocks in that area.

To lay 34 blocks is between 1£-1.50= £34-51
34 blocks is 14quid
Sand& cement £10

Total £65-75 and that's it built where as the sips need labor on top of the material costs.

Going by this, block built is cheaper.

 

[mikeey84]

This is an estimate.

Roughly 34 blocks in that area.

To lay 34 blocks is between 1£-1.50= £34-51
34 blocks is 14quid
Sand& cement £10

Total £65-75 and that's it built where as the sips need labor on top of the material costs.

Going by this, block built is cheaper.

Need to factor in insulation, which admittedly is probably not going to add a huge amount, but still take it closer...

 

[23vc]

Plus your other skin of block/brick, insulation etc. Time to put up a single 8x4 SIP panel vs time to build cavity wall of that area..

 

[^woody^]

You can't base prices on raw material costs. What is the frame being cladded with - brickwork, cheap plastic shiplap or expensive cedar? What about lintels required with masonry but not a frame, the type of insulation, the type of internal plaster finish? The detailing around openings and ancillary components

The cost of labour for a brickie or gang or a specialist timber frame carpenter (yes he will charge more). How does this translate in terms of time, so are you paying less hourly cost but for longer, so it saves nothing?

And are you basing timber frame on expensive factory SIPS, plus delivery and craning, or some OSB and CLS from Wickes, knocked up in the garden?

If you want to be smart, the heating costs over a 5 year period - including the smaller radiator you will need in a timber framed room? Or even the maintenance costs for say cladding over the same time? Annual insurance premiums for a risky timber frame over masonry?

So its not easy to work out but if you are going to work it out you need to do it properly, and not base calculations on limited or notional costs and m2 of a wall - that only works if doing large scale repetitive building.