Has anyone here built with 200mm cavity?

johnpawl

Hi, just wondering has anyone here built a house with a 200 mm cavity and pumped it, using quinn blocks or similar to minimise cold bridge to foundation and cavity closer? Like to hear from someone else who has gone this route and might be now living in the house to hear if they're happy with it? I'm thinking of going with oil and rads, also with a stove. I'm also thinking of laying underfloor pipes and leaving them there so I could connect them up if the heat pumps etc prove successful in years to come. Any advice greatly appreciated as I'm finally at the stage where I need to make some irreversible decisions! Thanks.

Carlow52

On the heating IMO u need to decide now as the cost of rads and UFH is not minor.

I would also consider insulated foundations

fclauson

Before you decide on this 100 or 200 or 300mm have you done some modelling

See below - what is intersting that a 200mm cav using quinlite is only marginally better than concrete block - and the block is cheaper, more stable, easier to work, and you can hang things from it more easily

for concerete read regular concerete block

Wall - 100 Concrete - 300 Cavity - 100 Quinn 0.51 mm 0.10 U-value
Wall - 100 Concrete - 300 Cavity - 100 Concrete 0.50 mm 0.11 U-value
Wall - 100 Concrete - 250 Cavity - 150 Quin 0.51 mm 0.11 U-value
Wall - 100 Concrete - 250 Cavity - 100 Quin 0.46 mm 0.12 U-value
Wall - 100 Concrete - 225 Cavity - 100 concrete 0.43 mm 0.14 U-value
Wall - 100 Concrete - 200 Cavity - 100 Quin 0.41 mm 0.14 U-value
Wall - 100 Concrete - 200 Cavity - 100 concrete 0.41 mm 0.15 U-value
Wall - 100 concrete - 150 cav - 215 quinlite 0.48 mm 0.16 U-value
Wall - 100 concrete - 150 cav - 150 quinlite 0.41 mm 0.17 U-value

ALSO NOTE - anything not build to TDG docs will need an engineer to sign off on.

johnpawl

Carlow52 wrote: »

On the heating IMO u need to decide now as the cost of rads and UFH is not minor.

I would also consider insulated foundations

Would it be expensive to just lay the pipes and let them there?

johnpawl

fclauson wrote: »

Before you decide on this 100 or 200 or 300mm have you done some modelling

See below - what is intersting that a 200mm cav using quinlite is only marginally better than concrete block - and the block is cheaper, more stable, easier to work, and you can hang things from it more easily

for concerete read regular concerete block

Wall - 100 Concrete - 300 Cavity - 100 Quinn 0.51 mm 0.10 U-value
Wall - 100 Concrete - 300 Cavity - 100 Concrete 0.50 mm 0.11 U-value
Wall - 100 Concrete - 250 Cavity - 150 Quin 0.51 mm 0.11 U-value
Wall - 100 Concrete - 250 Cavity - 100 Quin 0.46 mm 0.12 U-value
Wall - 100 Concrete - 225 Cavity - 100 concrete 0.43 mm 0.14 U-value
Wall - 100 Concrete - 200 Cavity - 100 Quin 0.41 mm 0.14 U-value
Wall - 100 Concrete - 200 Cavity - 100 concrete 0.41 mm 0.15 U-value
Wall - 100 concrete - 150 cav - 215 quinlite 0.48 mm 0.16 U-value
Wall - 100 concrete - 150 cav - 150 quinlite 0.41 mm 0.17 U-value

ALSO NOTE - anything not build to TDG docs will need an engineer to sign off on.

I was thinking of 100mm conc block, 200mm pumped cavity, 100mm conc block. I was thinking of a row or 2 of quinnlites underneath DPC to prevent cold bridging to foundation and a row of quinns above joists underneath cavity closer to prevent cold bridging at that junction...

feckincrazy

Hi. Just seen your post. If i was to advice you on your heating system go with just yer normal rads. Oil is exspensive at the moment but it is still alot more econamical than underfloor heating. With yer tradiational oil heating you are just heating a room. With underfloor heating you are heating a 200mm concrete floor screed. a 100 mm screed is poured the underfloor pipes are laid then another 100mm screed is placed. hence it will take along time before heat generates into room. double radiators incorporate convectors now which radiate heat into room more. also under floor heating is very exspensive from the use of esb. As a room heater i would maintain stanley stoves are the most econamical form of heating. back boilers can be used as well. hopefully this is of benefit to you.

fclauson

There are a number of different approches to UFH - the make up mentioned above is one

but there are also approches where you put insulation under the screed and just heat the screed - hence they are quicker to react

JB81

Hi there

I have built a bungalow with a 200mm pumped cavity wall, 100mm concrete on the outer leaf, and 150mm concrete block on the inner leaf ( as per engineer recommendations ). Only difference was the longer wall ties and slightly more of them than normal. I also used a quinnlite block At floor level, and one as a cavity closer to lessen cold bridging as much as possible.

In relation to the heating, i have underfloor heating installed with 150mm insulation underneath it, and a 75mm screed poured over it, so will only be heating 75mm of concrete, which i feel is good in that it will not take too long to heat up, but will also hold the heat longer ( the earlier post of heating 200mm of floor does not sound too economical to me ).

I will be running the UFH with an air-to-water heat pump ( being installed this week ), and i have spoke to some people which have had them installed and they were very happy with them over the recent cold snap and winter. I have done my research and spoke to existing customers of the model i am getting. And from my limited knowledge on the technical side i feel it is the ideal system to use to run underfloor heating, in that why heat water to 60-70 degrees with a boiler to cool it again before it goes into the underfloor, when the heat pump will only heat it to the temperature needed. Also i personally love the comfort of underfloor heating over a radiator anyday. I have also installed an air-tightness membrane system, and have put in a MHRV system as well.

Add this to the additional insulation in the house, i feel i will have an economical system ( hopefully!! ). Will keep posting in the self build thread on my experiences.

Thanks
Jb

fclauson

JB

what did you do for your windows
a) how did you close the cavity around the window
b) how did you hang the windows to be as cold bridge free as possible

Francis

JB81

Hi there fclauson

Without trying to sound stupid, if i told you how it was done i would be lying, i had a good engineer and a good builder and they worked between themselves as i would not have too much knowledge on the building side itself.

Sorry for not being much help

JB

johnpawl

JB81 wrote: »

Hi there

I have built a bungalow with a 200mm pumped cavity wall, 100mm concrete on the outer leaf, and 150mm concrete block on the inner leaf ( as per engineer recommendations ). Only difference was the longer wall ties and slightly more of them than normal. I also used a quinnlite block At floor level, and one as a cavity closer to lessen cold bridging as much as possible.

In relation to the heating, i have underfloor heating installed with 150mm insulation underneath it, and a 75mm screed poured over it, so will only be heating 75mm of concrete, which i feel is good in that it will not take too long to heat up, but will also hold the heat longer ( the earlier post of heating 200mm of floor does not sound too economical to me ).

I will be running the UFH with an air-to-water heat pump ( being installed this week ), and i have spoke to some people which have had them installed and they were very happy with them over the recent cold snap and winter. I have done my research and spoke to existing customers of the model i am getting. And from my limited knowledge on the technical side i feel it is the ideal system to use to run underfloor heating, in that why heat water to 60-70 degrees with a boiler to cool it again before it goes into the underfloor, when the heat pump will only heat it to the temperature needed. Also i personally love the comfort of underfloor heating over a radiator anyday. I have also installed an air-tightness membrane system, and have put in a MHRV system as well.

Add this to the additional insulation in the house, i feel i will have an economical system ( hopefully!! ). Will keep posting in the self build thread on my experiences.

Thanks
Jb

Hi, thanks for the rplies. Just wondering if I go with similar wall detail to JB but with rads, would it still be ok? Or if I had rads would I be better with insulated slabs??

BryanF

Re: how one might fix windows in wide cav
http://www.boards.ie/vbulletin/showthread.php?p=71303904

30 something

JB81 wrote: »

Hi there

I have built a bungalow with a 200mm pumped cavity wall, 100mm concrete on the outer leaf, and 150mm concrete block on the inner leaf ( as per engineer recommendations ). Only difference was the longer wall ties and slightly more of them than normal. I also used a quinnlite block At floor level, and one as a cavity closer to lessen cold bridging as much as possible.

In relation to the heating, i have underfloor heating installed with 150mm insulation underneath it, and a 75mm screed poured over it, so will only be heating 75mm of concrete, which i feel is good in that it will not take too long to heat up, but will also hold the heat longer ( the earlier post of heating 200mm of floor does not sound too economical to me ).

I will be running the UFH with an air-to-water heat pump ( being installed this week ), and i have spoke to some people which have had them installed and they were very happy with them over the recent cold snap and winter. I have done my research and spoke to existing customers of the model i am getting. And from my limited knowledge on the technical side i feel it is the ideal system to use to run underfloor heating, in that why heat water to 60-70 degrees with a boiler to cool it again before it goes into the underfloor, when the heat pump will only heat it to the temperature needed. Also i personally love the comfort of underfloor heating over a radiator anyday. I have also installed an air-tightness membrane system, and have put in a MHRV system as well.

Add this to the additional insulation in the house, i feel i will have an economical system ( hopefully!! ). Will keep posting in the self build thread on my experiences.

Thanks
Jb

hi Jb, i was very interested in your post. How is your heating system working? I'm interested in the insulation part too - do you find the UFH good?

beyondpassive

200 pumped bead cavity has been done by many over the last few years, 275 and 300mm is becoming normal now. However you need to deal with the rising wall and eaves cold bridges and window placements. Underfloor works very well with ultra low energy build, as (with MHRV) you can use your solar panel to heat the house for the shoulder months and a keep the cylinder topped up at around 50 degrees in winter for a stable heat in the ground slab using slow response thermal mass and stable comfort temperatures. This is becoming the standard solution for new builds. After November 2011 all new builds in planning will be to this spec. Rads are cheaper yes, but take up space and need to run at higher temperatures and don't make as good use of your thermal inertia. With underfloor in a low energy house, because the MHRV is distributing heat, you only need underfloor to about 1/4 of the floor area. With 2 or 3 low temp towel rails and maybe a post heater battery in the MHRV, you can heat the house to a high comfort level. Take a whole house approach to comfort rather than looking at individual components in Isolation for the most effective way to get a comfortable, cheap to run home at a moderate capital cost.

JB81

Hi 30 something,

Sorry for not replying sooner,
I love the UFH, and in my opinion is far more comfortable and controllable that rads. Due to the time of year, i do not have much to report on the results of all me insulation and heating investment, but in 6 months time i hope to see the benefits

Thanks
JB