SIP floor ventilated or not

[paul1974]

Hi,

 

building a garden studio with SIP panels. Floor and walls 100mm, roof 150mm.

Size is 4x3m

 

The base is a full concrete slab same size 4x3m. 150mm subbase + 100mm concrete (not insulated)

 

Can I:

a) lay the SIP floor on the concrete with a DPM membrane in between? Membrane will be wrapped up the wall 1 foot height.

or

b) do i have to ventilate between the concrete base and the SIP floor? Also using a membrane to wrap the base. 

 

I'm trying to minimize height, so i'd rather go with option a) if possible, but not sure re the ventilation. 

If i have to go with option b), what size gap? and can i use lines of bricks rather than wooden rafters to avoid wood degrading over time?

 

Not an expert, so thanks for any help.

 

Paul

 

 

 

 

[SuperJohnG]

Firstly. Welcome to the forum. 

 

I've never heard of a SIP floor being used ever? Why do you want that? 

 

If it for insulation then just use insulation? An idea of your planned build up would be helpful here. 

Edited February 22, 2021 by SuperJohnG

[paul1974]

Thank you.

 

It comes as a kit. See here: SIPs Panels | SuperSIPs UK Manufacturer of Structural Insulated Panels | Design I

 

I think if I was building a wooden frame I would have gone with normal insulation on a floating floor. 

I'm opting for this kit for convenience and time really...

 

Cheers

[Iceverge]

I'd do away with the concrete slab and use a  pier and beam foundation or a strip foundation with block rising walls. 

 

I wouldn't rest timber based products on the ground DPM or not.  If not ventilated and in contact with the ground it will rot.

[paul1974]

i wasn't keen on pier and beam foundation (or ground screws even) mainly because of pests/rodents potentially nesting under there. but i may reconsider. 

 

55 minutes ago, Iceverge said:

strip foundation with block rising walls

With this strip approach, not sure if i understand exactly, but is there concrete strips dug along the ground and then blocks on top of these strips?

 

I tried to represent below my understanding, but please correct me: 

 

[Iceverge]

Topsoil removed around the perimeter to create a trench. Pour filled with ready-mix concrete. Blocks built to elevate the sips to leave ventilation underneath. 

 

It's the cheapest way if you have time to kill and don't mind a bit of suffering.  To create a rodent proof base.

 

I would just leave it high enough that a cat could get in there! 

[scottishjohn]

sips floors used often in russia where permo frost is prevalent -- house is built on plies and then all sips construction floors walls and roof 

you will find plenty of examples on u-tube of DIY houses constructed this way 

using both OSB panels and MGO ones

Edited February 24, 2021 by scottishjohn

[jfb]

I had a garden studio shed built out of SIPs including the floor and installed by a couple of Canadians where it is more common.

They just put in some concrete piers and built off that. I didn't worry about vermin underneath and didn't have a problem (or maybe I just didn't notice the damage being done!).

 

Anyway if the concrete base isn't already installed I'd definitely do that - much cheaper and provides the ventilation it needs.

[paul1974]

So, I opted for a full reinforced concrete slab in the end... the ground here moves so much and wanted to be safe.

 

I was thinking to use engineering bricks in between concrete and SIP floor to provide a 65mm ventilation gap.

 

- Do i still need to run a DPM strip on top of the bricks or are these meant to stop moisture?

- Do i go for complete rows of bricks (laid at opposite length to the floor panels) or do i miss every other to provide added ventilation?

- would 600mm centres rows of bricks be ok?

- The concrete was finished pretty flat and smooth (used a large bull float) however i'm sure there will be a few mm imperfection along the surface. Should i maybe use sand or just packers where the level is too off?

 

Thanks again