UFH pipe clip rail etc

[MortarThePoint]

We have concrete* that is going to be directly under the screed with UFH in. On the Ground floor,  the concrete is 50mm thick* with insulation below and a gas membrane above. Consequently, I can't use staples to hold down the pipes. I think that leaves the conventional options being:

• Insulated panels: don't want the insulation or bounce possibility
• Castellated panels: expensive ~£7-10/m2. seem very expensive when you multiply by the m2 needed. It's about 3x the cost of the pipes themselves which doesn't feel right given the restraint is to last about a day before the screed then holds everything in place.
• Clip rails: ~£1.90/m2. These feel like a good solution, but on the GF I'd have to rely on the self adhesive backing of the clip rail track.

We plan to use a thin Anhydrite screed, 40-50 mm of Thermio+. We are not looking for a highly responsive system as using ASHP.

 

Does anyone have experience of how well the clip rail tracks stick down? I could add screws to hold them down on the FF, but not GF. Do the pipes want to pull the clips off and make it a nightmare?

 

I think I saw somewhere that some lay reinforcement mesh and then zip tie the pipes down. It's around £2.30/m2 for A142 mesh and has a good weight (2.2kg/m2) to it which would help hold the pipes down.

 

* Thermobeam

[ToughButterCup]

4 minutes ago, MortarThePoint said:

... I could add screws to hold them down on the FF, ...

 

Just a thought. Will you need UFH upstairs?

I ask because I have read other threads where more experienced SBs have decided against - UFH upstairs might well be unnecessary ? 

[MortarThePoint]

Just now, ToughButterCup said:

 

Just a thought. Will you need UFH upstairs?

I ask because I have read other threads where more experienced SBs have decided against - UFH upstairs might well be unnecessary ? 

 

I've touched on that in another thread and I'd like to have it on FF as we are likely to use the attic above and I don't want to risk having to have the GF too hot to make the 2nd F nice.

[ToughButterCup]

We solved that issue with a small electric mat - £50, trickle of warmth every now and then . Very cheap, hassle-free.

[Dudda]

I don't quiet understand the floor build up. Is this correct:

• 50mm Anhydrite screed with UFH
• Gas / Radon Membrane
• Insulation
• Sub floor of some type

Why not do what everyone else does and have the following:

• 50mm Anhydrite screed with UFH
• Slip membrane (light sheet of plastic to stop the liquid screed seeping down between the gaps in the insulation.
• Insulation
• Gas / Radon Membrane
• Sub floor of some type

This way the radon layer is protected by the insulation. If you put the Radon on top of the insulation you'll have pipes, UFH installers walking across it, some type of UFH clips, potentially steel mesh to clip the UFH onto, etc. The Radon layer will get damaged.

The other advantage of having the Radon layer below the insulation is you're keeping the insulation dry. If the Radon layer is the main waterproof layer rising damp can lower the thermal performance of the insulation.

In terms of installing the radon it shouldn't impact any DPC levels or anything else it's just dressed up the side of the insulation to whatever height you want.

The other advantage is Radon is a thick layer that can be difficult to work with and get flat. Having the large insulation sheets flattens it down. You won't be able to do that with a liquid screed and any bulges, folds or creases in the radon layer will lead to thinner Anhydrite screed in areas where cracks will form. This isn't an issue when using a lighter slip membrane.

[MortarThePoint]

2 minutes ago, Dudda said:

I don't quiet understand the floor build up. Is this correct:

• 50mm Anhydrite screed with UFH
• Gas / Radon Membrane
• Insulation
• Sub floor of some type

Why not do what everyone else does and have the following:

• 50mm Anhydrite screed with UFH
• Slip membrane (light sheet of plastic to stop the liquid screed seeping down between the gaps in the insulation.
• Insulation
• Gas / Radon Membrane
• Sub floor of some type

This way the radon layer is protected by the insulation. If you put the Radon on top of the insulation you'll have pipes, UFH installers walking across it, some type of UFH clips, potentially steel mesh to clip the UFH onto, etc. The Radon layer will get damaged.

The other advantage of having the Radon layer below the insulation is you're keeping the insulation dry. If the Radon layer is the main waterproof layer rising damp can lower the thermal performance of the insulation.

In terms of installing the radon it shouldn't impact any DPC levels or anything else it's just dressed up the side of the insulation to whatever height you want.

The other advantage is Radon is a thick layer that can be difficult to work with and get flat. Having the large insulation sheets flattens it down. You won't be able to do that with a liquid screed and any bulges, folds or creases in the radon layer will lead to thinner Anhydrite screed in areas where cracks will form. This isn't an issue when using a lighter slip membrane.

 

The stack up is:

• Insulation (325mm EPS)
• Precast Concrete (50mm)
• Gas Membrane
• Slip Membrane (if needed)
• Screed with UHF (~40mm)

 

[Dudda]

12 minutes ago, MortarThePoint said:

 

The stack up is:

• Insulation (325mm EPS)
• Precast Concrete (50mm)
• Gas Membrane
• Slip Membrane (if needed)
• Screed with UHF (~40mm)

Thanks. I don't understand what the ~50mm of precast concrete is doing. This can't be a structural layer at that thickness. What's under the insulation and what layers are already in place? I still think it would be better if the Gas / Radon layer was below the insulation.

[MortarThePoint]

Just now, Dudda said:

Thanks. I don't understand what the ~50mm of precast concrete is doing. This can't be a structural layer at that thickness. What's under the insulation and what layers are already in place? I still think it would be better if the Gas / Radon layer was below the insulation.

 

It is quite a new product that is structural and has beam components, but the reinforced web is 50mm. It and the gas membrane are installed, but nothing on top yet.

 

[Dudda]

I understand now. The 375mm insulation isn't 100% insulation but is an insulated beam system and the 50mm concrete is a structural screed that ties it all together. To late but I'd have put the radon below this.

 

In you're case I'd use the clip rail tracks and just stick them to the concrete. I've stuck them to just the slip membrane and they worked fine. When you've all the UFH pipes in place they tend to all click together to form a giant web that doesn't move and the weight (when you've the pipes pressurized and filled with water to test for leaks prior to pouring the screed) ensures they don't lift or move.

[MortarThePoint]

11 minutes ago, Dudda said:

In you're case I'd use the clip rail tracks and just stick them to the concrete

 

I can't do that directly as the gas membrane is there but hopefully it will stick well.

 

1 hour ago, Dudda said:

The other advantage is Radon is a thick layer that can be difficult to work with and get flat. Having the large insulation sheets flattens it down. You won't be able to do that with a liquid screed and any bulges, folds or creases in the radon layer will lead to thinner Anhydrite screed in areas where cracks will form.

 

This comment concerned me a bit. Do you think the weight of the tubes will help out?

[Dudda]

1 minute ago, MortarThePoint said:

 

I can't do that directly as the gas membrane is there but hopefully it will stick well.

 

 

This comment concerned me a bit. Do you think the weight of the tubes will help out?

Sorry I meant to say stick to the radon. They stick very well as it's a smooth flat surface they're sticking too.

 

 

It just will means you'll have to pay extra care and attention to getting it flat and even. If you've a giant space that's flat its easier but if you've a lot of load bearing internal walls or popup's it makes it more time consuming. Just pay extra care to getting it flat and even and folding it tight into the corners. The weight of the filled UFH pipes will help.

[LA3222]

@MortarThePoint the clips don't stick for toffee! I did my first floor ufh a couple of weeks ago and used clips, had to screw them down.

 

 

[PeterW]

1 hour ago, MortarThePoint said:

is quite a new product that is structural and has beam components, but the reinforced web is 50mm. It and the gas membrane are installed, but nothing on top yet.

 

your radon layer is in the wrong place. If you have beam / block or beam / EPS in your case, you ventilate the under floor cavity. 
 

[MortarThePoint]

1 hour ago, LA3222 said:

@MortarThePoint the clips don't stick for toffee! I did my first floor ufh a couple of weeks ago and used clips, had to screw them down.

 

Do you remember what brand of clip rail track you used?

[LA3222]

1 hour ago, MortarThePoint said:

 

Do you remember what brand of clip rail track you used?

I got mine from Wunda. The sticky bit was a bit like double sided tape, probably works on foil faced insulation etc but useless in wood and probably concrete I expect. 

[SuperJohnG]

5 hours ago, LA3222 said:

I got mine from Wunda. The sticky bit was a bit like double sided tape, probably works on foil faced insulation etc but useless in wood and probably concrete I expect. 

I used the wunda clip track also. Stuck great on the EPS, although where there was a kick at the loops I used staples also. If you screw the clip track down it will work OK, just a bit long winded but you'd only need a few screws per clip track.