Garden Office base/floor suggestions or comments please?

[rs6mra]

Hi Guys,

I am planning on building an office in my garden on an existing patio covered with concrete slabs. It's going to be 14'x10' & I would appreciate your comments or suggestions on the base.
Bearing in mind I already have the concrete slabs laid, I plan on using a pre cast concrete deck pier/deck block on which I would place the 4x2 frame with joists 16" on centre. I would then use 75mm polyurethane foil back insulation and then 18mm t&g OSB to cover the entire area. The vapour barrier I was thinking would be placed between the deck block and the 4x2 frame.

1. Is this the best place for the vapour barrier?

2. The reason for using the deck block was to raise the structure off the slabs for circulation - is this a good or bad move?

3. Would installing the frame onto damp proof membrane suffice? Resulting in me getting rid of the deck block.

Thanks in advance for your comments.

 

[jeds]

I can't work out what a 'pre cast concrete deck pier/deck block' is. Which makes it a bit difficult to comment. And what materials will the office to be built from?

 

[freddiemercurystwin]

and a plywood deck.

 

[rs6mra]

I can't work out what a 'pre cast concrete deck pier/deck block' is. Which makes it a bit difficult to comment. And what materials will the office to be built from?

It will be built out of timber 4x2 and here is a pic of the pre cast concrete deck:

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• rs6mra
• 20 Feb 2013
• 1

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[freddiemercurystwin]

Why not just use ordinary concrete blocks, it won't blow away!

 

[rs6mra]

Why not just use ordinary concrete blocks, it won't blow away!

I suppose that would work but would it be a good idea to mount the structure on blocks? I cannot understand why or how important it is to have air circulate underneath the structure...... any suggestions as to the benefits? Thanks

 

[jeds]

I see. So it's a timber building. It wouldn't do any harm to fit small sheet of poly between the timber and the block - although it's probably not necessary. If there is continuous ventilation below the floor you don't need a dpm. The vapour barrier must be on the warm side of the insulation. My advice would be timber joists overboarded with treated OSB or similar. Insulation can go directly on top of that with vapour barrier over and then finish with a floating floor of 18mm P5 grade moisture resistant T&G chipboard. If you want to get rid of the deck blocks ordinary concrete blocks - or maybe engineering bricks - would do the job just as well.

 

[luisdesign]

Raising the timber is less about allowing air flow and more about trying to keep the timbers off the floor (and thus dry).

You have to be wary raising the base too high though, because this may encourage animals to crawl under there... such as foxes and cats (and in some areas, rats) etc... In that sense, if you do raise the deck significantly you want to add some form of pest barrier...

Area you building this garden office from scratch or buying a pre-made shed like thing?

 

[rs6mra]

Thanks guys and my thinking now is to forget about the concrete deck/blocks/bricks and go with the timber frame placed on top of DPM & if I have understood you guys correctly, there should be no issues here?

I will be building this from scratch.

Is T&G chipboard the same as OSB?