Floor Insulation

[Jeremy Harris]

1 hour ago, Ferdinand said:

 

In that situation you could also have used a structural plinth (as they used to be done), which would spread the load, or even used an island with a flat bottom.

 

Or made the legs shorter and just sat it on a sheet of 18mm or 22mm plywood with the plinths round the side hiding it.

 

Ferdinand

 

 

 

I sat our island on a bit of 18mm ply, with the plinths and side and back panels covering the edges.  I didn't do this to spread the load, the ply was there to locate the island.  I just stuck the ply to the floor with a few dabs of silicone, then put the island on top, as a free standing unit.  The ply locates it and stops it moving, although there the thing is so heavy that I don't think it would have moved anyway.  The legs rest on the ply, so the load is spread, although I didn't need this particular quality.

[ProDave]

1 hour ago, Jeremy Harris said:

 

 

I sat our island on a bit of 18mm ply, with the plinths and side and back panels covering the edges.  I didn't do this to spread the load, the ply was there to locate the island.  I just stuck the ply to the floor with a few dabs of silicone, then put the island on top, as a free standing unit.  The ply locates it and stops it moving, although there the thing is so heavy that I don't think it would have moved anyway.  The legs rest on the ply, so the load is spread, although I didn't need this particular quality.

Our island is completely free standing.  It's sheer weight ensures it is not going anywhere.  Though it may be "helped" to go for a bit of a walk after completion sign off, when silly circulation spaces might not apply any more (cough)

[ryder72]

17 hours ago, Ferdinand said:

 

In that situation you could also have used a structural plinth (as they used to be done), which would spread the load, or even used an island with a flat bottom.

 

Or made the legs shorter and just sat it on a sheet of 18mm or 22mm plywood with the plinths round the side hiding it.

 

Ferdinand

 

Yes after the event and in hindsight but that doesnt solve the problem with a faulty floor.

 

We always use 18mm marine ply on chipboard floors.

[Ferdinand]

16 hours ago, ProDave said:

(cough)

 

?

[canalsiderenovation]

Ok, I've had a reply from the builder.

 

I Have spoken with Wunda (they are the company that we have used for the last 10 years) regards the product that you have mentioned below. Its unfortunately not the right product for this application. It can be incorporated but it’s not the most cost effective. Are you averse to electric UFH to your existing floors? I have had an idea that would give you the same 100mm PIR board that will be going in your extension floors (see sketches attached. Our printer/scanner is offline so I had to take a photograph of them). The only section where the electric UFH would meet the water UFH in the extension is the open plan kitchen/dining room. This room would be spilt into two zones anyway so I don’t think it would be a problem. The electric UFH obviously pulls on your electricity more and you may prefer the water type UFH so the ASHP can run it. You could have 100mm PIR board with water UFH. It would leave you a finished ceiling height of 2155mm which is not an issue from a building regs point of view.

I personally think the 75mm would be the best option in terms of U value and a slightly higher ceiling height but it’s your decision. We will obviously price up whatever you decide.

 

*****

 

I've attached the pics but I can't really see them well.

 

I'm not keen on electric for our existing, it's quite a large area and in my view defeats an ASHP but anyone got any suggestions?

 

 

Edited March 18, 2020 by canalsiderenovation

[canalsiderenovation]

So I guess if I'm reading this correctly if we want thicker insulation we would probably have to dig up our existing concrete pad....

[PeterW]

He’s got a thing about screed..! Electric UFH can cause issues with LVT so it is not something I would use. 
 

To use the Wundatherm system for LVT or Karndean you use Duo boards over the top - not cheap but works fine. 

[canalsiderenovation]

2 minutes ago, PeterW said:

He’s got a thing about screed..! Electric UFH can cause issues with LVT so it is not something I would use. 
 

To use the Wundatherm system for LVT or Karndean you use Duo boards over the top - not cheap but works fine. 

I'm really put off by electric underfloor heating and LVT gluedown flooring is non negotiable. I'd rather stick with 'wet' UFH.

 

When you say he has a thing about screed do you mean he's using too much so he should reduce the screed and add more insulation? I'm feeling a bit out of my depth here but want to ensure we have the right about of insulation. I'd rather not dig up 100m2 plus of existing flooring.

 

Any advice or help would be great, my main worries for the whole build is heating and insulation and windows, the latter I feel more confident with but this part is not something I have any knowledge of.

[PeterW]

No he just keeps drawing options with screed - you don’t need to use it ..! 
 

There are loads of wet floor overlay options - if I get chance I’ll ring Wunda tomorrow and speak to Andy and see what he suggests. 
 

Other option is the Fermacell floor system over the track panels. Again, not cheap but works well. 

[canalsiderenovation]

1 minute ago, PeterW said:

No he just keeps drawing options with screed - you don’t need to use it ..! 
 

There are loads of wet floor overlay options - if I get chance I’ll ring Wunda tomorrow and speak to Andy and see what he suggests. 
 

Other option is the Fermacell floor system over the track panels. Again, not cheap but works well. 

 

Ah thanks so much that would be amazing, private message me if it's easier. Cost wise I'm sure it's got to be better than digging up our floors. I don't want to go to the expense of putting in ASHP, triple glazed windows and wall insulations if the floor insulation is going to be insufficient.

 

Our current ceiling height in our living room is 2.6m and the hall and bedroom areas is 2.35m (they vary because our property is like two bungalows seperated by a flat roof and the bungalow part with the bedrooms have steps).

[PeterW]

So it’s definitely a solid concrete floor now ..? And you’re happy that you can go upward on door frames ..?? Get the 150mm additional clearance ..?

[canalsiderenovation]

38 minutes ago, PeterW said:

So it’s definitely a solid concrete floor now ..? And you’re happy that you can go upward on door frames ..?? Get the 150mm additional clearance ..?

 

Yep it's a solid concrete pad 1970s, some areas have wooden bits where the pipes are for our oil heating which is being ripped out (see pics) which when the heating worked (for about a month, would heat up the wood bits which was a bit weird). All door frames, skirting, plaster all coming off so makes no difference (and not all doors staying in same place anyway).

 

Edit: Building Report from when we purchased it says:

 

The floors throughout the property are solid concrete construction. There are ducts within the floor slab to allow the central heating pipework. These sections of the floor have a timber board over them in order to protect the pipework.The floors were generally found to be level with no evidence of any significant 
settlement. Some slight unevenness was noted to the surfaces but this is 
considered to be within normal building tolerances.

 

Edited March 18, 2020 by canalsiderenovation

[canalsiderenovation]

As an update to this, how does this sound? This would be breaking out our existing flooring:

 

150mm MOT sub base

150mm concrete oversite

120mm Kingspan insulation

Polythene separating layer

60mm screed incorporating UFH pipework

 

[PeterW]

Bin the oversite, it is not needed !!

 

150mm sub base

25mm EPS as blinding carried up the existing walls as expansion

DPM

130mm PIR

100mm concrete with UFH

 

Stronger and quicker than the screed insulation sandwich. 

[canalsiderenovation]

6 minutes ago, PeterW said:

Bin the oversite, it is not needed !!

 

150mm sub base

25mm EPS as blinding carried up the existing walls as expansion

DPM

130mm PIR

100mm concrete with UFH

 

Stronger and quicker than the screed insulation sandwich. 

 

Is the oversite needed due to our gluedown LVT? What is EPS? So PIR is the insulation then? Is this likely to be more expensive? Sorry, this is new to me...

Edited April 6, 2020 by canalsiderenovation
Edit

[PeterW]

Over site is not needed at all ... it is a hangover from standard construction methods where the slab was laid first and then a final screed laid when the levels of doorways etc was known. I doubt your screed would be flat enough for LVT unless they use a liquid screed (that has its own issues) so I would be banking on a 3-5mm self leveling compound finish later prior to LVT which is much cheaper than a 150mm layer of concrete. 
 

PIR - Kingspan/Celotex/Xtratherm Insulation

EPS - . Polystyrene insulation (Jablite among others)

 

You can use sand as a blinding layer over stone but EPS is just as good and gives you an extra insulating layer. 
 

 

 

[canalsiderenovation]

20 minutes ago, PeterW said:

Over site is not needed at all ... it is a hangover from standard construction methods where the slab was laid first and then a final screed laid when the levels of doorways etc was known. I doubt your screed would be flat enough for LVT unless they use a liquid screed (that has its own issues) so I would be banking on a 3-5mm self leveling compound finish later prior to LVT which is much cheaper than a 150mm layer of concrete. 
 

PIR - Kingspan/Celotex/Xtratherm Insulation

EPS - . Polystyrene insulation (Jablite among others)

 

You can use sand as a blinding layer over stone but EPS is just as good and gives you an extra insulating layer. 
 

 

 

 

Perfect thanks! Much better than the 75mm option.

[canalsiderenovation]

@PeterW the comments re the oversite and what you mention above - if the builder would excavate our existing floors, would your proposal for the 'new' extension be the same. This is what is being proposed for the new by the builder, marginally different to the proposal I mentioned above which was the excavation of our existing:

 

New extension

 

o    150mm MOT sub-base 
o    100mm concrete oversite 
o    300MU DPM 
o    100mm Kingspan insulation 
o    Polythene separating layer 
o    65mm liquid screed incorporating UFH pipework 
 

[PeterW]

Still not getting this idea of oversite and only 100mm insulation. Also, liquid screed and adhesive based flooring really don’t work well with laitence issues. 

[canalsiderenovation]

43 minutes ago, PeterW said:

Still not getting this idea of oversite and only 100mm insulation. Also, liquid screed and adhesive based flooring really don’t work well with laitence issues. 

 

So for the new extension area it would also be best doing:

150mm sub base

25mm EPS as blinding carried up the existing walls as expansion

DPM

130mm PIR

100mm concrete with UFH

 

And then the self levelling compound for the gluedown LVT.

[PeterW]

@canalsiderenovation it makes more sense to use the same construction method all the way through the house then you will get your levels the same. May need expansion joints at any significant direction changes - from memory you have three distinct blocks - and using sleeved rebar at the joins will stop any settlement movement. 
 

It would be a really simple job to do as a one piece pour with something like Aguila or another flowing / self compacting concrete over the top of the UFH. As you’ve got to pump your concrete deliveries anyway due to the bridge, this will be a win/win both sides. 

[canalsiderenovation]

1 hour ago, PeterW said:

@canalsiderenovation it makes more sense to use the same construction method all the way through the house then you will get your levels the same. May need expansion joints at any significant direction changes - from memory you have three distinct blocks - and using sleeved rebar at the joins will stop any settlement movement. 
 

It would be a really simple job to do as a one piece pour with something like Aguila or another flowing / self compacting concrete over the top of the UFH. As you’ve got to pump your concrete deliveries anyway due to the bridge, this will be a win/win both sides. 

 

Thanks @PeterW I've gone back to the builder with this proposal.