Outbuilding construction

[Mr_T25]

Looking to build a small outbuilding of about 15m to 20m2 for general use / gym. Few questions:

1. I am undecided whether I want to use blocks or brick facing. Will I see much insulative properties by using thermalite blocks compared with bricks?

2. To keep the cost down I was thinking of making it single skin rather than double. Any concerns with that?

3. Was planning to go with 50mm celotex boards compared with 100mn. Is this inadvisable?

Would you answer be any different if the overall size was to be around 30m2?

 

[John D v2.0]

1 and 3, the celotex will make a much bigger difference to the insulation than the type of block.
Building in block will be more difficult for diy (or expensive to get a brick layer) and the materials will be heavy. Have you thought about timber frame with cladding as that's a popular choice for diy outhouses.
Single skin would be OK as long as it's stable enough, if it's that small it won't need much buttressing, and then you only need to take care of weather tightness.

 

[^woody^]

You need to change the way you are thinking about this.

You wonder about the insulation qualities of brick and block, but then mention using 50mm insulation and not 100mm.

You want to keep costs down by building a single skin, and then mention a larger building.

Define your requirements and priorities, then work out a design that meets them.

 

[Mr_T25]

I wont be building this myself, will be getting a builder but have been given a few price options based on the above factors.

 

[Mr_T25]

1 and 3, the celotex will make a much bigger difference to the insulation than the type of block.
Building in block will be more difficult for diy (or expensive to get a brick layer) and the materials will be heavy. Have you thought about timber frame with cladding as that's a popular choice for diy outhouses.
Single skin would be OK as long as it's stable enough, if it's that small it won't need much buttressing, and then you only need to take care of weather tightness.

For my understanding why will blocks be more expensive? I would have thought there is less labour involved due to bigger size blocks v smaller bricks? Also we're looking at the termalite blocks not the heavy concrete ones.

 

[John D v2.0]

I mean block compared with timber frame. But I was assuming you could diy timber frame. If you're getting someone else to do it and the price is good, then go for it. Block is more secure than timber unless you put in metal lath somewhere. Also it's more durable (not affected by damp)

 

[^woody^]

For my understanding why will blocks be more expensive? I would have thought there is less labour involved due to bigger size blocks v smaller bricks? Also we're looking at the termalite blocks not the heavy concrete ones.

Building in blocks is about two thirds of the cost of bricks per m2. But as thermalite blocks are not weather resistant, once you add the cost of render, it becomes more expensive per m2. And then you have cyclical maintenance and limited life of the render.

The questions that you should be asking yourself are,

Are you bothered about looking at brick or looking at block?

Are you bothered about maintaining rendered block or timber cladding?

Are you bothered about the comfort and costs of keeping the inside warm ?

... and then compare the answers to whatever budget you have.

The cheapest option is a timber frame, as this wont need deep foundations. This will also give the best insulation values. But you then need to decide on a cladding material.

A builder who does mainly brickwork, wont give a good price on a timber frame though. Likewise for a carpenter and brickwork