150mm for insulation and floor screed

selfbuildsoon

Hi all. Our BER says that our ground floor is to consist of 100mm insulation and 50mm screed and our engineer has mentioned that 50mm sand and cement is not enough. So we are wondering are there any other options instead of reducing the amount of insulation in the floor(e.g. self-levelling screed etc.)? We don't have underfloor heating.

sydthebeat

do you have a sub floor under the insulation? at what point in the build are you?
do you have working (construction) drawings of the build?

kieranhr

You can put in a self-levelling screed down to a depth of 35 mm. According to a lot of manufacturers, anything more than that is a waste. You'll find them with a google search.

sydthebeat

kieranhr wrote: »

You can put in a self-levelling screed down to a depth of 35 mm. According to a lot of manufacturers, anything more than that is a waste. You'll find them with a google search.

you wont cover radiator pipes with 35 mm

the op needs to give more information i think

kieranhr

sydthebeat wrote: »

you wont cover radiator pipes with 35 mm

It's tight, but you will. Minimum recommended cover is 20 mm over pipework. Plus the OP has 50 mm to play with if he needs it.

sydthebeat

kieranhr wrote: »

It's tight, but you will. Minimum recommended cover is 20 mm over pipework. Plus the OP has 50 mm to play with if he needs it.

eh, i think you forgetting about a very major element here.... all radiator pipes have to be insulated if included in a floor slab.

plus there is no 50mm to play with either. The typical insulation requirement for floors today is 100mm..... which rises to 150 when UFH is incorporated.

kieranhr

sydthebeat wrote: »

eh, i think you forgetting about a very major element here.... all radiator pipes have to be insulated if included in a floor slab.

plus there is no 50mm to play with either. The typical insulation requirement for floors today is 100mm..... which rises to 150 when UFH is incorporated.

No, I'm not. The insulation is provided below the screed, and he doesn't have UFH. 100 mm is adequate for a floor slab without UFH, leaving him 50 mm for screed.

sydthebeat

kieranhr wrote: »

No, I'm not. The insulation is provided below the screed, and he doesn't have UFH. 100 mm is adequate for a floor slab without UFH, leaving him 50 mm for screed.

you should read up on the building regulations, specifically the conditions when radiator pipes are located in a floor slab.... because you are wrong here.

edit: also, the op hasn't confirmed if there is a sub floor to work with, so describing it as a screed may not be correct.

kieranhr

sydthebeat wrote: »

you should read up on the building regulations, specifically the conditions when radiator pipes are located in a floor slab.... because you are wrong here.

edit: also, the op hasn't confirmed if there is a sub floor to work with, so describing it as a screed may not be correct.

I'm a chartered engineer of twelve years experience and I know the Building Regulations inside out, thanks Syd. The part of the regulations you're referring to is paragraph 1.4.4.1 of Part L, and it states that hot water pipes should be insulated unless they contribute to heat requirement of the dwelling, which they do in this case, as they are above the floor insulation.

sydthebeat

kieranhr wrote: »

I'm a chartered engineer of twelve years experience and I know the Building Regulations inside out, thanks Syd. The part of the regulations you're referring to is paragraph 1.4.4.1 of Part L, and it states that hot water pipes should be insulated unless they contribute to heat requirement of the dwelling, which they do in this case, as they are above the floor insulation.

thats not the part of the building regulations i am referring to.

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,18691,en.pdf

these are the requirements for heating systems in domestic houses

kieranhr

sydthebeat wrote: »

thats not the part of the building regulations i am referring to.

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,18691,en.pdf

these are the requirements for heating systems in domestic houses

An interesting document, but 1) not part of the building regulations, and 2) out of date. 2011 are the current regulations in force.

Anyway, selfbuildsoon, I think you know what you're going to do at this stage.

sydthebeat

kieranhr wrote: »

An interesting document, but 1) not part of the building regulations, and 2) out of date. 2011 are the current regulations in force.

Anyway, selfbuildsoon, I think you know what you're going to do at this stage.

they are as valid a "guidance" document, as the technical "guidance" document Part L. Check environ.ie

also, the section you quoted 1.4.4.1 specifically states
"Pipes and ducts which
are incorporated into wall, floor or roof
construction should be insulated."

you cannot get any more clear cut than that.

selfbuildsoon

Hi all, house nearly plastered so need to decide soon. Thanks for all the help.

Rhys Essien

This is what you need.

http://www.cemex2go.com/supaflo/

sydthebeat

selfbuildsoon wrote: »

Hi all, house nearly plastered so need to decide soon. Thanks for all the help.

So do we take it that you already have a sub floor poured? Or not?

selfbuildsoon

Yes, have sub-floor in already.

sydthebeat

that begs the question why you didnt insulate and place rad pipes in sub floor?

in my opinion 50mm for a screed is WAY too small to put rad popes into... notwithstanding the fact they need to be insulated.

This screed at that depth will crack over the pipes.

i assume your window and door heights will only allow you another 150mm above subfloor?

wayoutwest

I thought that a screed that is being laid onto insulation has to be 75mm minimum if is a traditional screed [tamped down sand + cement] or 50mm, if is a pumped liquid screed - the latter,containing additives that make it stronger and therefore allow it to be thinner?.

Poor Uncle Tom

wayoutwest wrote: »

I thought that a screed that is being laid onto insulation has to be 75mm minimum if is a traditional screed [tamped down sand + cement] or 50mm, if is a pumped liquid screed - the latter,containing additives that make it stronger and therefore allow it to be thinner?.

The issue isn't the screed, it's the fact that you have insulated pipework within the 50mm depth.

DOCARCH

I know some my be horrified for this suggestion (just trying to help the OP) but couldn't the floor insulation be tracked/'chased' (only partially) and (insulated) heating pipework liad partially in floor insulation a sufficient depth to provide integrity to the screed.

Not ideal, I stress that!

wayoutwest

A 1/2" heating pipe+ thickness of armafex is not going to buried by 50mm of screed....surely it has to be sunk into the insulation by chasing out the foam ?. I've screeded over 2" kingspan before -the insulated pipework fitting snuggly within it,allowing a full thickness of screed to be laid above it.

DOCARCH

wayoutwest wrote: »

A 1/2" heating pipe+ thickness of armafex is not going to buried by 50mm of screed....surely it has to be sunk into the insulation by chasing out the foam ?. I've screeded over 2" kingspan before -the insulated pipework fitting snuggly within it,allowing a full thickness of screed to be laid above it.

Yes, that's basically what I said above.

Not in anyway an ideal way to go, but may be one of only a few solutions.

selfbuildsoon

So would it be alright to put the radiator pipes on top of the sub-floor and then put the insulation on top and then use 50mm of sand and cement screed? Or would we be better using less insulation(90mm instead of 100mm) and 60mm of sand and cement screed, as the homebond manual says you need 65mm when laid directly on top of insulation? I've read that a 10mm aggregate can help reduce curling.

sinnerboy

Don't reduce insulation ! Layer it. Stagger joints to counter risk of curling.

And don't place un insulated pipes in direct contact with the sub floor.

Instead -
Layer 1 *50mm PIR board - with 50mm thick x 150mm high vertical upstand to floor edge . No chases. No gaps.
Layer 2. 50mm PIR board with chases only as required for insulated pipes.
¬System underlay
*50mm PFA screed.

¬ PFA supplier will install this , to his spec.
* PFA screeds can be reduced sometimes to 40mm. Take heed of the suppliers advice here. If this is possible increase Layer no 1 to 60mm.

selfbuildsoon

Thanks, but if the pipes in contact with the subfloor were insulated could we put the insulation on top of them? I'm presuming the screed you've mentioned is one of the self-levelling ones?

sydthebeat

selfbuildsoon wrote: »

Thanks, but if the pipes in contact with the subfloor were insulated could we put the insulation on top of them? I'm presuming the screed you've mentioned is one of the self-levelling ones?

you want to put heating pipes UNDER insulation???

I give up.....

selfbuildsoon

That's what I said to somebody and they said as long as the pipes were lagged/insulated it was fine!

sydthebeat

selfbuildsoon wrote: »

That's what I said to somebody and they said as long as the pipes were lagged/insulated it was fine!

It makes no sense at all if you think about it, the practicalities don't work.

sinnerboy

selfbuildsoon wrote: »

That's what I said to somebody and they said as long as the pipes were lagged/insulated it was fine!

"somebody" is wrong....

shedweller

Can i add my pure layman 2 cent?

Take a hot water pipe and lag it. Then wrap it in more lagging. A while later, stick your hand under the outer layer of lagging. It will be hot, wont it? My point is that all insulation transmits some heat. So it makes more sense to me to have the pipes embedded in the floor insulation. In it, not under or over.
I personally don't like the idea of pipes embedded in floor screed because it will soak up heat from the heating system before it gives it to the rads. And when i turn on the heating i want heat now, not when the floor is finished soaking heat. Unless i have near passive insulation with hrv etc etc. the heat from the floor is not going to be of any use to me. Technically it will but along the lines of a gnats fart!

My 2 cent.

sydthebeat

shedweller wrote: »

Can i add my pure layman 2 cent?

Take a hot water pipe and lag it. Then wrap it in more lagging. A while later, stick your hand under the outer layer of lagging. It will be hot, wont it? My point is that all insulation transmits some heat. So it makes more sense to me to have the pipes embedded in the floor insulation. In it, not under or over.
I personally don't like the idea of pipes embedded in floor screed because it will soak up heat from the heating system before it gives it to the rads. And when i turn on the heating i want heat now, not when the floor is finished soaking heat. Unless i have near passive insulation with hrv etc etc. the heat from the floor is not going to be of any use to me. Technically it will but along the lines of a gnats fart!

My 2 cent.

hi shedwelder,

The pipes are supposed to be lagged (insulated) even when they are placed OVER the floor insulation.
The floor insulation is there to stop heat loss from the house to the ground.
The lagging on the pipes is there to stop heat loss from the pipes to the concrete screed.

In the situation described above, everyone is in agreement that chasing the pipes INTO the insulation is about the only option left, and IS NOT ideal.

about2build

You may get away with 60mil screed but that is the limit-in fact my plumber has insisted on 75 mil ground and 1st floor....oh and pipes must be lagged....you want the heat going to the rads not the ground, the screed or anywhere else

selfbuildsoon

So just to get this right- are the pipes to be put between the two layers of insulation or can they be chased into the top part of the top insulation layer and then covered with screed?

sydthebeat

what does your certifier suggest? as they will know the holistic situation whereas we can only comment in isolation.