Floor insulation - small gap, small question

BarneyMc

I've attached a photo showing a close up of my perimeter insulation (50mm) on my ground floor. Unfortunately my builder cut it quite short so in some places the liquid screed might come up and over the perimeter insulation.

The polythene (not yet laid) will at least stop it getting into the space between the perimeter insulation and the underside of the plaster. However, to plug this gap with some sort of 'insulation' would it be a good idea to spray some expanding foam and then trim it off before the polythene goes down?

hexosan

No need to trim it. The plastic with stop it. The screed isn't pumped at any force and will barely have the pressure to push against the plastic.

BarneyMc

hexosan wrote: »

No need to trim it. The plastic with stop it. The screed isn't pumped at any force and will barely have the pressure to push against the plastic.

So go ahead and spray expanding foam but don't bother trimming? Would it not be better to trim and leave it easier to apply the skirting board later (square corner)?

hexosan

BarneyMc wrote: »

So go ahead and spray expanding foam but don't bother trimming? Would it not be better to trim and leave it easier to apply the skirting board later (square corner)?

Sorry thought it but didn't type it. I meant no need spray foam. How short is the insulation

BarneyMc

hexosan wrote: »

Sorry thought it but didn't type it. I meant no need spray foam. How short is the insulation

It's just short in some places... maybe 5mm or so but didn't spend too much time analyzing. I've used a lite block there on that row anyway so I suppose it's very minor. It's just that it wouldn't take much effort to spray now if it would be of any benefit.

hexosan

Like everything on these self builds I think we go a little ott but if your time is free do it for piece of mind. You should also just duct tape a small thin strip of cardboard to the ins where it's cut low.
It barely has the force to move the plastic. If I get a chance tomorrow I'll email you a pic of mine.

chillit

hi barney

Can I ask a perhaps stupid question but I will ask anyway. You seem to have your walls completed before you pour the floor. Does this mean you have some type of subfloor and now you are just pouring a final floor. I ask because I always thought that the floor was poured as soon as the footings and radon barrier were installed. In order to protect the radon barrier while the block work continued.

Apologies if this is a crazy question.

delfagio

chillit wrote:

Can I ask a perhaps stupid question but I will ask anyway. You seem to have your walls completed before you pour the floor. Does this mean you have some type of subfloor and now you are just pouring a final floor. I ask because I always thought that the floor was poured as soon as the footings and radon barrier were installed. In order to protect the radon barrier while the block work continued.

Hi chillit,

Typically houses been built nowadays will install a subfloor with radon barrier usually under this subfloor.

Then after house is built and plastering internal is complete, floor insulation is laid and a finished screed is poured on top to give the finished floor. This screed can have UFH in it or not depending on heating type used.

BarneyMc

delfagio wrote: »

Hi chillit,

Typically houses been built nowadays will install a subfloor with radon barrier usually under this subfloor.

Then after house is built and plastering internal is complete, floor insulation is laid and a finished screed is poured on top to give the finished floor. This screed can have UFH in it or not depending on heating type used.

Sort of. I had to use pre-cast slabs for my sub floor. Before the walls were built on this, strips of radon barrier were laid and the walls built on top. Then the other day the radon barrier was taped to these strips, insulation laid, etc.

delfagio

BarneyMc wrote:

Sort of. I had to use pre-cast slabs for my sub floor. Before the walls were built on this, strips of radon barrier were laid and the walls built on top. Then the other day the radon barrier was taped to these strips, insulation laid, etc.

Good man Barney, when's D Day for finishing now....

BarneyMc

delfagio wrote: »

Good man Barney, when's D Day for finishing now....

End of the summer. Have to say I'm finding it tough going. Can't wait to get all wrapped up and in. The floors are proving to be difficult but hope to get them poured within a few weeks.

Anyone else finding it tough going?

delfagio

BarneyMc wrote:

Anyone else finding it tough going?

Yes I found it tough going myself when we were building, especially coming towards the end as I just felt drained of energy from it all. But perseverance is key to getting there.

BarneyMc wrote:

End of the summer. Have to say I'm finding it tough going. Can't wait to get all wrapped up and in. The floors are proving to be difficult but hope to get them poured within a few weeks.

Brilliant, end of summer. I know how you feel about the floors, because I done the UFH, insulation and perimeter insulation myself, it took forever as I could only do it at evenings and weekends. What I thought would take a couple of weeks took months ha. I almost lost the will to live. I had arranged the screed fours times and kept having to cancel it.

BarneyMc

delfagio wrote: »

Yes I found it tough going myself when we were building, especially coming towards the end as I just felt drained of energy from it all. But perseverance is key to getting there.



Brilliant, end of summer. I know how you feel about the floors, because I done the UFH, insulation and perimeter insulation myself, it took forever as I could only do it at evenings and weekends. What I thought would take a couple of weeks took months ha. I almost lost the will to live. I had arranged the screed fours times and kept having to cancel it.

My builder put the external air duct for the stove in the wrong position in the floor. He just assumed it would go in position x. Anyway it will have to be ripped out next week and repositioned. STRESS! :mad:

delfagio

BarneyMc wrote:

My builder put the external air duct for the stove in the wrong position in the floor. He just assumed it would go in position x. Anyway it will have to be ripped out next week and repositioned. STRESS!

Lovely....there's always something

BarneyMc

Here's 2 pics of the external air pipe as it is. My intention was to have it rear its head further into the room and straight up into the stove via the underneath external air source entry point. The diagrams at the top of the first page here shows the 2 entry points.

I can either ask my builder to rip it out and re-position OR perhaps I can just leave as is and put a 90 degree bend on it and just bring it into the stove via the rear external air source entry point. Although this puts yet another bend on the duct it means not having to rip through my floor again and perhaps leaves my options open as to which stove to fit?

893bet

Move it! Not that big a job! You will be glad you did when it's done.

delfagio

My pipe ended up about 5" away from where it had to come up to be directly under the stove so I had to put 2 x 90degree bends on to bring it to the right spot

BarneyMc

delfagio wrote: »

My pipe ended up about 5" away from where it had to come up to be directly under the stove so I had to put 2 x 90degree bends on to bring it to the right spot

What a pain. So do you think I should move my pipe now?

delfagio

BarneyMc wrote:

What a pain. So do you think I should move my pipe now?

If you feel you should then go for it. I suppose if you don't you might regret it, plus it's easier to do everything now than later. In my case I had no choice. I had to get it bang on centre under the stove.

I did it before I poured floor screed, so I had 200mm depth between the insulation and screed, and just had to break out small amount of the concrete subfloor in order to get the bends lower than finished screed level.

Calahonda52

BarneyMc wrote: »

Here's 2 pics of the external air pipe as it is. My intention was to have it rear its head further into the room and straight up into the stove via the underneath external air source entry point. The diagrams at the top of the first page here shows the 2 entry points.

I can either ask my builder to rip it out and re-position OR perhaps I can just leave as is and put a 90 degree bend on it and just bring it into the stove via the rear external air source entry point. Although this puts yet another bend on the duct it means not having to rip through my floor again and perhaps leaves my options open as to which stove to fit?

Maybe too late for commentary...

will rear entry not push stove out to far into room?

Bottom entry would be a lot neater but it would have to be inch perfect, or even mm perfect

maybe leave a bit of room around it if u redo it and use a straight multiwick

BarneyMc

Calahonda52 wrote: »

Maybe too late for commentary...

will rear entry not push stove out to far into room?

Bottom entry would be a lot neater but it would have to be inch perfect, or even mm perfect

maybe leave a bit of room around it if u redo it and use a straight multiwick

Going to the stove shop tomorrow so hope to get some pro advice on it. Will report back!

Calahonda52

BarneyMc wrote: »

Going to the stove shop tomorrow so hope to get some pro advice on it. Will report back!

Good.
in passing, I am hoping to retire soon so would you ever get this project done, it keeps me awake at night:D:D:D:D

BarneyMc

Calahonda52 wrote: »

Good.
in passing, I am hoping to retire soon so would you ever get this project done, it keeps me awake at night:D:D:D:D

That makes 2 of us!!! :pac:

chillit

Hi

Can I ask what is the advantages of pouring the floor in the way you have. I.e main floor slab (sub floor) then insulation then a smaller 70-80mm screed.

My spec has the old style with the following makeup. Hardcore, sand, radon barrier, 150mm insulation, plastic membrane, 150mm concrete slab, floor coverings.

Would there be any advantage to switching the approach

BarneyMc

chillit wrote: »

Hi

Can I ask what is the advantages of pouring the floor in the way you have. I.e main floor slab (sub floor) then insulation then a smaller 70-80mm screed.

My spec has the old style with the following makeup. Hardcore, sand, radon barrier, 150mm insulation, plastic membrane, 150mm concrete slab, floor coverings.

Would there be any advantage to switching the approach

I really don't know but I suppose you only have one 'floor' as such and will save there. 150mm concrete slab seems like a lot for a finished floor - lots of thermal mass but maybe too much? Maybe start a new thread to get some feedback.

BarneyMc

BarneyMc wrote: »

Going to the stove shop tomorrow so hope to get some pro advice on it. Will report back!

OK, was in Belfast yesterday to inquire about the 2 stoves I was initially interested in - the Spartham Ambiente A1 and HWAM 3640. Both are expensive coming in at around €2,800 and both will mean moving the air inlet pipe. Both however are certified airtight.

The shop owner also introduced me to this Thorma Andorra stove (no connection to this website) which retails at around about €1300. The only entry for external air however is via the rear and not the bottom but it would just mean putting a bend on my pipe as it sits in the floor. Although not certified airtight, on examination it looked very good and will ultimately reply on the seal for airtightness.

What has everyone else in the 'airtightness' boat done - gone out and splashed a fortune on a certified airtight stove or just got a decent one at a fraction of the price?

MicktheMan

BarneyMc wrote: »

What has everyone else in the 'airtightness' boat done - gone out and splashed a fortune on a certified airtight stove or just got a decent one at a fraction of the price?

My thoughts on the subject is as follows and tbh I have no direct experience with airtight stoves but rather a "normal" stove in an air tight house.

Anyone who installs an airtight stove probably also has a mvhr unit. As there are two fans in these, one will fail first. You have a 50:50 chance that it will be the supply fan which will put the house into negative pressure. Now, this may not occur until, for arguments sake, year 15. After 15 years, how airtight will your air tight stove be considering the number of times the door has been opened & closed, service history etc?
So whatever you do choose, make sure that your CO monitors/alarms are properly installed and functional.

893bet

MicktheMan wrote: »

My thoughts on the subject is as follows and tbh I have no direct experience with airtight stoves but rather a "normal" stove in an air tight house.

Anyone who installs an airtight stove probably also has a mvhr unit. As there are two fans in these, one will fail first. You have a 50:50 chance that it will be the supply fan which will put the house into negative pressure. Now, this may not occur until, for arguments sake, year 15. After 15 years, how airtight will your air tight stove be considering the number of times the door has been opened & closed, service history etc?
So whatever you do choose, make sure that your CO monitors/alarms are properly installed and functional.

I have similar thoughts. Just went with two stoves that have an option for 100% external air. Installed 7 CM alarms.

Off topic but if a fan fails in the MVHR how do you know? Should an alarm sound?

BarneyMc

893bet wrote: »

I have similar thoughts. Just went with two stoves that have an option for 100% external air. Installed 7 CM alarms.

Off topic but if a fan fails in the MVHR how do you know? Should an alarm sound?

Are they certified air tight or just standard and what price bracket if you don't mind sharing?

893bet

BarneyMc wrote: »

Are they certified air tight or just standard and what price bracket if you don't mind sharing?

One is around 800 (can't remember name)

Other around 1200 (ACR Neo 3p).

BarneyMc

893bet wrote: »

One is around 800 (can't remember name)

Other around 1200 (ACR Neo 3p).

So you're going with the notion that a stove is as airtight as the seal which should be fine for years and when not can be replaced anyway?

893bet

BarneyMc wrote: »

So you're going with the notion that a stove is as airtight as the seal which should be fine for years and when not can be replaced anyway?

Pretty much. And also that I will keep the MVHR serviced. And I have adequate CM alarms to detect a failure.

THE DON FANUCCI

does the perimeter insulation go on both sides of the internal walls also?

BarneyMc

THE DON FANUCCI wrote: »

does the perimeter insulation go on both sides of the internal walls also?

Yip, it sure does.

BarneyMc

Jumping on a few months... floors are in now 4 weeks and inside all painted with initial base layers. Anyway, so the painters could spray the bottom of the walls, I untaped the polythene at the walls and let it fall onto the floors - this was done about 2 weeks ago.

Yesterday I noticed some dampness under the polythene where the floor moisture couldn't escape. Anyway I suppose I should cut this off now anyway so it's not visible above the floor level? Also, I suppose I need to cut the perimeter insulation so it's flush with the finished floor also?

Before any tiling, etc. I will apply wall-floor airtightness tape. Will it stick ok to the perimeter insulation or I suppose as long as it's stuck to the wall and floor it will be ok?

MicktheMan

You will need to use a primer on the floor prior to applying the tape. Prime the insulation as well and you should have no issues.

Make sure that the tape does not cut the wall to floor corner, i.e. that you leave a 90 deg angle such that when the tiles are laid into the wall, the tape won't be in the way.

BarneyMc

MicktheMan wrote: »

You will need to use a primer on the floor prior to applying the tape. Prime the insulation as well and you should have no issues.

Ok, I spoke to a supplier of this tape and they didn't mention the primer. I suppose it depends on the specific tape used?

MicktheMan wrote: »

Make sure that the tape does not cut the wall to floor corner, i.e. that you leave a 90 deg angle such that when the tiles are laid into the wall, the tape won't be in the way.

Yip, good call!

MicktheMan

BarneyMc wrote: »

Ok, I spoke to a supplier of this tape and they didn't mention the primer. I suppose it depends on the specific tape used?

From my experience, a primer would be very important for this detail. I would be suspect of any product not requiring one.

Calahonda52

BarneyMc wrote: »

Ok, I spoke to a supplier of this tape and they didn't mention the primer. I suppose it depends on the specific tape used?

Am with MtM here re the need for a primer, is the supplier just a reseller or someone who knows what they are about?
You also need to clean off the plaster ridges at the bottom of the walls to make the taping easier.
Is this first floor or ground?

BarneyMc

Calahonda52 wrote: »

Am with MtM here re the need for a primer, is the supplier just a reseller or someone who knows what they are about?
You also need to clean off the plaster ridges at the bottom of the walls to make the taping easier.
Is this first floor or ground?

This is a supplier who specialises in this type of stuff. In fairness I didn't explain in detail - I just mentioned floor-wall junction. It's ground floor.

Calahonda52

BarneyMc wrote: »

This is a supplier who specialises in this type of stuff. In fairness I didn't explain in detail - I just mentioned floor-wall junction. It's ground floor.

Grand, if you want to PM me the product name I am happy to give my opinion...

The theory behind the primer is that they can then design the tape adhesive so as it can have a life expectancy of up to 60 year, knowing that there wont be a substrate problem.

The testing that is done is when the material fails, not the adhesive.

Currently there is no agreed COP for these tapes

Again, don't mix and match products from different suppliers

ferryman35

The primer does make a super difference to the end result. Also you can get a nozzle for the adhesive that applies multiple beads of adhesive in parallel. 'Roll' the tape in with a rubber roller and you have a super job.

Calahonda52

ferryman35 wrote: »

The primer does make a super difference to the end result. Also you can get a nozzle for the adhesive that applies multiple beads of adhesive in parallel. 'Roll' the tape in with a rubber roller and you have a super job.

+1

Just checked with the folk Barney contacted and yes the primer is required on the concrete and pb, first needs to be brushed or vacuumed clear of dust and be dry.

applying the adhesive to the floor and plaster separately from the barrier is a better idea than applying tapes with full adhesive as it give much more control: the tapes are so sticky that they are immovable once the touch anything really.

BarneyMc

I had the guy who has done the airtightness stuff so far in this week and he's doing up a quote for this work. He has done a great job to date so I think it's best to let him finish and get me ready for the airtightness test.