Jetfloor detail

[RandAbuild]

Looking at @NSS blog http://strawberrytreelodge.blogspot.co.uk/2015/09/stage-3-jetfloor-topsheet-ufh-pipework.html , we have the same floor build up but are currently aiming to board out the Jetfloor and leave putting in the final insulation layer and ufh after the frame has gone up. This to to avoid damaging the ufh during erection of the timber frame.

 

Would this be better than putting in the insulation & ufh now?

[NSS]

Couple of points to bear in mind. You'll need a membrane over the beams and Jetfloor blocks (under the topsheet) which needs to extend over the perimeter wall (under sole plate of the timber frame) so this would need to go down before you board over the jetfloor/beams. My concern would be the vulnerability of that membrane to damage.

 

Secondly, assuming you will have internal walls that are structural, you'd need to bring any dwarf walls up to sole plate height before erecting the timber frame. This would have the effect of sub-dividing your floor for the structural concrete pour (which could make it more difficult to maintain consistent floor levels). 

 

One of the advantages of laying the ufh pipes and the structural concrete floor before erecting the walls is the ease of access, and the coursing blocks at the perimeter are perfect for leveling the floor to.

 

As you'll have seen from the photos, we marked the Jetfloor topsheet  with internal wall positions, doorways, shower trays, kitchen/utility cupboards, etc before laying the pipes. This ensured that no pipes were routed under any areas where fixings into the floor would need to be placed later.

[James13]

I am having this problem now as screeders dont seem to want to screed without the roof on, and the UFH will have to be laid and manifold in position without the roof/walls.

[NSS]

11 minutes ago, James13 said:

I am having this problem now as screeders dont seem to want to screed without the roof on, and the UFH will have to be laid and manifold in position without the roof/walls.

Hi James, just to be clear it is not a screed over the Jetfloor, it's a structural concrete pour (reinforced in our case with fibres as opposed to mesh). It is perfectly normal for the slab to be laid prior to shell erection, irrespective of whether it is a timber frame or traditional block & brick construction.

 

One other tip, it's worth using the aluminium cored ufh pipe as it stays where you clip it. Our groundworks contractor was a little concerned that the pipes would lift when they poured the concrete and insisted on having someone on standby to deal with if there was a problem - but there wasn't.

[James13]

Hi NSS - Who specified the 'structual concrete pour' as opposed to a sand and cement screed?

[NSS]

James, it is the manufacturers specification. From their brochure.....

 

The floor is completed with a structural concrete topping reinforced with polypropylene fibres laid over a minimum of 80mm eps sheet insulation.

Forterra Concrete specification:

• 70mm concrete strength class RC25/30

• Reinforced with polypropylene fibres or steel mesh reinforcement

[RandAbuild]

Thanks NSS - very useful

[James13]

@nss did you require anchor straps with this?

[NSS]

1 hour ago, James13 said:

@nss did you require anchor straps with this?

Assuming you mean for anchoring the timber frame to the foundation, no. Scandia-Hus simply Rawl-bolted the sole-plate to the coursing blocks. That said, we're in a very sheltered location so windage isn't a significant issue. If your location is more exposed then you may choose to use straps.

[NSS]

4 hours ago, RandAbuild said:

Thanks NSS - very useful

 

Glad to help :-) 

[James13]

Thanks Guys.  @RandAbuild what did you put under your frame? - I am looking at the foam glas as per @NSS

[RandAbuild]

@James13 I was going to use Marmox Thermoblock, but in the end we used 2 courses of 7N blocks.

[James13]

Thanks @RandAbuild - I am leaning towards this due to cost. Jet floor recommend this so I hope it will not affect the thermal qualities of then build to much.

 

 

[NSS]

Hi James, whereabouts in the UK are you? I have a small amount of Perinsul and a fair bit of Foamglass left over from our build which you could have (for a small consideration) if it would help.