Finer details of subfloor

getfit

I'm looking to break ground in the next month or so and have gotten my head around 90% of the build process up to floor level.

Fully happy with my grasp of foundations
wall thickness x 3, steel reinforecement, 30N mix etc., then get the rising walls going, put in soil pipes and radon outlets, inlets for water pipes etc. while rising wall being laid. Then you have hollowcore, radon sump, sand, radon barrier and DPM, insulation (probably go over 100mm) and then pour concrete floor.

The two gaps in my knowledge/questions I have, relate to:
a) what is the sory with the pipe work for the central heating system/water system? is it a case the plumber will chase the floors 6/8 months down the line when he needs to, or, do the pipes need to be laid prior to floor being poured
b) The floor that is laid as per my little list of jobs - is this the "final floor" or is it common to factor in that a final screed will be laid after the shell has been built?

I know these are fairly simplistic questions, but I want to have every aspect of the process clear in my mind before I proceed

dingdong1234567

a)The heating pipes will be poured in the concrete floor. Chasing the floors for heating pipes is maddness (cost wise). And is bad building practise at best!

Generally you can do it either way, i.e pour a screed after the concrete is poured. But your increasing the cost here by pouring an extra screed. Also for this you would have to lower your make up of the sub-floor to allow for the screed on top.Where a really good finished concrete floor would do the job.

sinnerboy

make sure buried pipes are 1 . insulated and 2. jointless

also if you do this - from ground up

150 hardcore ( with radon sumps + pipes )
50 sand
radon barrier
150 concrete

and STOP

you can now first fix and make sure you are happy with rads power points etc locations .
if you place two x 60mm layers of kingspan simply omit channels in the top layer for pipes
(still sleeve pipes in insulating pipe wrap ) and 75mm screed over . U Value 0.2

A NICE DETAIL - if you are dry lining is to take the pipes from the floor up the dry lining cavity ( still wrapping pipes where you cut away other insulation ) so the pipes "pop out" from the wall not the floor . Looks neater + easier to vaccuum around rad



ALSO

think about all the services you are taking into the house

gas water esb ntl - locate at least 6 ducts , with draw wires in you utility ( all sealed to radon barrier ) .

you can drag services in below the fllor slab now - no fuss no muss . It you have 1 or 2 too many ducts at completion - just foam them up .

don't forget a drain point for the ( possible ) kitchen island unit ( again - if not need later - foam it up )

getfit

Thanks lads.

Glad to hear I'll only need to pour one floor and just get it right first time...

Dreading the thought of sorting a plumber so early in the process.. How would that operate in a normal situation. Would I just price a guy for the whole job and get him to do this part of it now or would I literally pay someone to just do this basic pipe work in the floor and then start from fresh later on pricing plumbers.

dingdong1234567

getfit wrote: »

Thanks lads.

Glad to hear I'll only need to pour one floor and just get it right first time...

Dreading the thought of sorting a plumber so early in the process.. How would that operate in a normal situation. Would I just price a guy for the whole job and get him to do this part of it now or would I literally pay someone to just do this basic pipe work in the floor and then start from fresh later on pricing plumbers.

No, get your plumber to price for the whole lot. It is the plumber that should be flexable, ie come to site before the pipes need to be installed in the floor. After this you might not need him back until the first fix plumbing starts.

Get a fixed price of him for the job IMO. It works better for the man signing the cheques.....YOU!

AckwelFoley

i poured a sub floor and then put in a 3" dry mix screed when house was plastered.

Its a nightmare at best to keep the floor clean if you are not there to clean as you go.

But its a better job to do it in one job as stated... so i would go with the one

sinnerboy

consider using a PFA screed ( "easi screed" )

install after joinery second fix and decoration - no floating ( to speak of ) no mess . it's really good . get the supplier to install the lot i.e. holding membrane and tapes and pour on the screed .

it works best with UFH as screed is only 40mm thick ( faster thermal response )

Mellor

What about cracking of the screed as its so thin? There are minimum thicknesses for floating screeds in TGDs, do they have a IAB cert for use over UFH?
I have seen them or similar used before (in extension in family house), but was over a slab so different min thickness.

sydthebeat

The thin screed systems are almost specifically designed for UFH systems.... the make up is pulverised ash material and doesnt have any cement in it, thus it has an expansion coefficient much greater than concrete and doesnt (*shouldnt*) crack.

Mellor

sydthebeat wrote: »

The thin screed systems are almost specifically designed for UFH systems.... the make up is pulverised ash material and doesnt have any cement in it, thus it has an expansion coefficient much greater than concrete and doesnt (*shouldnt*) crack.

Are you sure about this?
I am vaugely familar with PFA, but as far as I was aware was that it was an aggregate. It replaces traditional aggregates thus making the concrete light weight. It still has cement in it*. And has a lower expansion coefficent. The lower weight would reduce dead loads and so reduce section thickness for beams.
I'm sure its perfectly fine for use as a screed, but if it is going below the min limits it would be good practice to look for a IAB cert.




*Are you thinking of GGBS, which replaces cement in concrete. It is ground slag from steel production. As opposed to pulverised flue ash from coal.

dingdong1234567

PFA is Pulverised Feul Ash its a by product of electirc stations from burning coal. It is used by most of the cement manufacturing companies in this country to make cement more workable.

sydthebeat

http://www.easyscreed.ie/_easyScreed/heatingCost.html

When traditional concrete is used as a floor screed a minimum depth of 75mm-100mm is required to prevent cracking. In comparison, the minimum depth required for EasyScreed is only 35mm. This is because it has no cement in it and consequently won't crack. The benefit of a thin layer of screed means it can conduct heat very quickly and therefore more cost effectively.

I have to go by what information manufacturers supply, maybe this product is GGBS but i was under the impression it was PFA....

Mellor

Nobody suggested is was anything other than Flue ash from coal. But I don't think its to make it more workable.

I have a feeling that people are refering to different products. There are a number of various concrete and/or screed materials.

Maybe people could post a link for products they have used, as I said I am only familar with PFA as an aggregate. I have seen calcium silicate based screeds that can go to very small thicknesses, even a few mm. Generall refered to leveling compounds, in theory could be used over UFH thinner that the min, this is cover by a BS afaik

dingdong1234567

Mellor wrote: »

Nobody suggested is was anything other than Flue ash from coal. But I don't think its to make it more workable.

Nor did i Mellor, this is fact as i worked on a Cement factory for two years. Therefore i would kow a bit about the auld cement craic.

Mellor

Read my mind re the above (was typing as you posted), thanks for posting the link syd.
I have a feeling it may be a Calicum silicate based one, but I can't find any info to say if it is PFA, GGBS or CS.

Mellor

dingdong1234567 wrote: »

Nor did i Mellor, this is fact as i worked on a Cement factory for two years. Therefore i would kow a bit about the auld cement craic.

Well, you learn something new everyday I suppose, I honestly had only heard of it used for lightweight reasons or environmental reasons like with GGBS. Could you post a link if available. That being said it appears we were both right, I got up some info on it here. Its used in a range of concrete and cement materials.

http://www.ukqaa.org.uk/EnvirAndSustain.html
http://www.ukqaa.org.uk/Pictures/AshUse.jpg

AckwelFoley

Jaysus, what happend to d 'ol sand and cement :rolleyes:

Mellor

snyper wrote: »

Jaysus, what happend to d 'ol sand and cement :rolleyes:

The modern world synper, everybody wants things thinner and sexier

muffler

Mellor wrote: »

The modern world synper, everybody wants things thinner and sexier

And what happened to "size matters"










muffler runs off and infracts himself for of topic posting

dingdong1234567

snyper wrote: »

Jaysus, what happend to d 'ol sand and cement :rolleyes:

And how! I blame the architects. They loose the run of themselves when its time to start specifing materials.;)

Mellor

dingdong1234567 wrote: »

And how! I blame the architects. They loose the run of themselves when its time to start specifing materials.;)

Agreed, but generally younger graduate types. Specifying trendy materials, this years "buzz" word. Last year was "Exposed concrete" and "iroko". What will 2008 bring.

tedser

im raising an area outside my back door,15 ft wide and 12 ft out but i need to come up 18inches,do i put in about 12 inches of gravel then concrete,or is there a better way,please help

Quazzie

tedser wrote: »

im raising an area outside my back door,15 ft wide and 12 ft out but i need to come up 18inches,do i put in about 12 inches of gravel then concrete,or is there a better way,please help

This might help. If after reading this you have any specific questions don't be afraid to ask. In terms of making up the 18 inches you could put in 12-15 inches of filling first. Just remember to make sure it is min. 150mm below floor level of the house as per regulations

tedser

Quazzie2002 wrote: »

This might help. If after reading this you have any specific questions don't be afraid to ask. In terms of making up the 18 inches you could put in 12-15 inches of filling first. Just remember to make sure it is min. 150mm below floor level of the house as per regulations

thanks for your reply,great help,could you tell me do i put the damp proof sheet under the filling or on top of it,and do i need to put rebar into it?

muffler

If its only for parking/walking/patio you wouldnt need any damp proofing. Depending on its use you could just make up 150mm of concrete or alternatively incorporate a couple of sheets of light steel mesh

tedser

thanks for your reply,1 more question what is the best way to raise up the shore with the ground im raising?can i buy plastic sleeves the same size as the cover 300mm square and 165mm square

muffler

Im not sure if Im reading your post correctly but if you mean supporting the fill and the concrete on top you could build a couple of rows of blocks around the perimeter, fill with stone/gravel and then your concrete on top. The blocks can then be plastered on the outer surface.

tedser

thanks v much for your information its been a great help,il send you a pic of it when its finnished if you like,cheers

muffler

Yeah, keep us updated. We always like to see how the jobs turn out.

tedser

no problem,just one more question you have been so helpful,what can i rub on or buy to make the shuttering come away from the concrete easy and smooth

Quazzie

If the shuttering has a flush side (laminated) rub diesel onto in liberally and it'll assist in seperateing it from the set concrete. It should stick too much anyways, so I wouldn't worry too much about it.