Pre-Pour of Finished floor

Salmon

Folks,

Can anyone offer advice on this one! I'm about to pour the finished floor screed and am a little concerned about how the insulation and steel mesh is installed. I'll try to upload a few pics but bear with me i havent done it before!

Insulation: http://picasaweb.google.com/paul.uineill/House/photo#5016196503659994338
and Mesh: http://picasaweb.google.com/paul.uineill/House/photo#5016196679753653490
My question is should the insulation be 'edged' around the external walls and is there enough mesh on top of the insulation?

Looking to pour tomorrow so any help would be great!

oneillk

hi,
its hard to make out form the photos but it looks a bit messy to be honest. It doesnt look like you have more than 100mm to top of the block from the top of insulation, i think it should be a min of 150mm with the steel mesh within the concrete. the mesh on the photo looks as though it is laying directly on top of the insulation, which is no good. it need to be laid on spacers about 30-50mm deep to allow the concrete to flow in and around it to become, essentialy, one unit. Also, yes you should have edge insulation.

Also, im not sure how the radon/dpm barrier has been laid, but your internal walls dont seem to be covered by it. all the walls should be covered so as not to allow for any radon leaks into the space.
Are the interal walls going to be covered with the slab or brought up to the same level as the external walls when pouring. If there not, it looks like it would be a pretty big area for one slab.

Not sure if that helps, just my opinion.

Salmon

Thanks for the comments!

Yeah I'll have to measure the height from the top of the insulation to the top of the block. Sorry I forgot to mention that the inner walls werent built as high as the external walls and there are soapbars which are layed on top of the radon barrier that you can see in the picture! Does anyone think its a good idea to get the edge insulation put in before pouring the floor. If I dont do it what are the downsides??

oneillk

if you dont put in the edge insulation your floor will be cold bridged along it entire perimeter. Which wont help when trying to keep house warm etc.

You definetly need it.

Salmon

oneillk,

Is the edge insulation just the same board as in the picture cut into strips and laid on its side, or is it a special board that I buy separately?

Mellor

Its the same stuff, its often thinner than the main insuluation under the floor, about 25mm. And as previously said, it has to be there

De_man

PM Sent


a pint of plain is yer only man

de_man

AJL

Hi

I have the TF part house sitting on a raised block about 130 mm above the slab. I have laid 60mm insulation on the floor. I have not put edge insulation in. The guy is coming to pour a 70 mm screed on Mon.
Any chance I can use 25 mm insulation and glue it around the edges of internal/external walls (sitting on top of the 60 mm slab insulation? This would save me having to take up all the insulation and cutting it to vertically shove down the 25 mm insulation.

Should be OK, just run some tape along the join to stop the concrete creeping under and lifting it.

Salmon

Folks,

does the steel mesh need to cover the entire surface of the poured concrete slab. I'm not sure why its required as there has been a lot of steel mesh placed in the foundations already! surely the most stress on the foundations will be acting vertically and not horizontally???

Any ideas?

De_man

hi salmon

i sent you a PM in case you need any info, but i reckon this would be
able to answer your questions

does the steel mesh need to cover the entire surface of the poured concrete slab.

no, its not necessary to cover the entire floor area, in my build i used spare sheets of A393 then used the "lighter steel mesh" A392? and lengths of 12mm rebar that i had lying around for the remainder, (saying that i possibly went "overkill" 35 Sheets of A393 and 250 lengths of rebar between the foundations and the floors and 120metres of concrete:eek: ) for the floors these were raised from the insulation by using stock bricks and some "mars bars" ensuring that i had 3" between the insulation and 3" from the top of the block (but saying that i've been told you'll get away with 5")

Ensure your insulation is not "rocking", if so, take up the sheet and put down sand to even up the surface on which it rests, you won't damage the radon barrier, otherwise when you pour there's a great possibility that the insulation will lift.

So you have your insulation put the bricks on top, then the mesh so you
should have 150mm between the top of the insulation and the top of the
external block, make sure though to keep the mesh away from where you intend to run your services, pipes etc.. otherwise you'll have an awful job in completing the chasing:eek:

before you pour do your best to ensure all mesh is tied and secured, trust me
when the concrete mixer starts pumping there's a lot of pressure on the sheets to move!!

regarding services, what's your plan? i made a complete B***** of my set
up, i put together box sections of 6X1's and put them down in the areas
where i intend to run the services, over half of them moved:mad:
the timber for same cost me 300euro what a waste, if i was doing it again
i'd listen to the brother and not to bother with the timber and just use a consaw to cut out the sections once the powerfloating was completed.

regarding the powerfloating, we poured on a fairly good day but it wasn't until 6pm before the floor was ready to powerfloat and we didn't finish until
3AM. (not a very good start to building relations with your neighbours)
before you pour arrange a powerfloater, generator and 2-3 halogens
as it'll be a long night


to avoid hastle powerfloating and if the weather if forecast to be wet you can ask your concrete supplier for an accelerator to be put in the mix, if not you can use "Glenium" Spelling?? (special order) but you have to get approval from your engineer to start messing around with the mix


one last thing make sure your supplier knows that the mix is for a finished floor say use smaller stones in the mix say 10/12mm max otherwise it'll be much harder to finish the floor


most importantly once completed get your engineer to check it before you
pour afterall he'll have to sign off on it for the mortgage


hope this helps,

sas

Is there any particular reason why the floor insulation couldn't be put in high enough to overlap with the wall insulation (avoiding the need for the edging) and then you screed on top of that?

I've been wondering this for a while.

Salmon

Thanks for the advice deman!

As far as I can see everything is ready to start on monday (pouring the floor!)I just need to get the 25mm insulation in place around the edges before the cement arrives! Its arranged for 10am and I am hiring a halogen lamp and bulb incase it runs into the wee hours!! Deman you said that you had 150mm between the top of the insulation and the top of the internal block on the cavity! I only have about 60mm! Does this sound ok? a 150mm screed seems like a lot! Whats the norm or is there a reg to cover this?

the brickie

sas wrote:

Is there any particular reason why the floor insulation couldn't be put in high enough to overlap with the wall insulation (avoiding the need for the edging) and then you screed on top of that?

I've been wondering this for a while.

what you are suggesting can be done except exactly backwards to what you said.if you raise the insulation in the floor to meet the wall insulation this will have the floor ins.level with your d.p.c.and following on, your conc.above your d.p.c.allowing damp into your slab through capillary action (rising damp).

so you get the blocklayers to put the last row of wallties in the footings one
block below dpc then when you start the house your first row of aeroboard
will be 225mm below your floor and so meeting up exactly with the underslab
aeroboard.
this is of course depending on a tidy job having been done on the radon
so the aeroboard andradon dont end up blocking your cavity .

De_man

Its arranged for 10am

just a suggestion why not phone the concrete company and demand an 8AM start, that's a pretty standard time, just had another look at your photos
i reckon 10am is too late!! you'll never finish it on time unless you're going to do a few rooms on day1 then complete on the next day

regarding the weather i've found the TV3 weather forecast on teletext very accurate go for the 5day forecast

I am hiring a halogen lamp and bulb incase it runs into the wee hours!!

Good stuff get 2 lamps it makes it much easier and of course don't forget to have the tea organised:D i had "senior management" on standby for that:D

you said that you had 150mm between the top of the insulation and the top of the internal block on the cavity! I only have about 60mm
Does this sound ok? a 150mm screed seems like a lot! Whats the norm or is there a reg to cover this?

i'm afraid you've a huge problem there, you don't have enough (unless your engineer is willing to chance it) i reckon the slab would crack when you put the blocks on it:eek: sorry but it's a non starter!!!

The regs state on page 42 of the house building manual (47 Yoyo available from easons on O Connell Street) state "150mm min thickness for ground supported concrete floor"

I'm must stress that i'm not a qualified engineer i've only a bit of experience from a couple of semis that i managed to get over the last few years and helping my family and friends out with their homes i'm presently building my own gaff doing a lot of the crap work and using direct labour for the parts i'm not sure of.

But in your situation i can only see the following solutions.

1. change your insulation (if you're using 100mm aeroboard) and use 60mm
kingspan high density (just about meets the regs) doing this will save you
40mm so you'll have say approx 100mm screed.
Personally, i can't see the supplier taking back insulation out of the packs
overall, i think this solution would be a waste of time and complete madness
and in the end your floor won't meet the regs and you'll have probs installing your services

2. consulting your engineer or brickie, i'd go for the most sensible option
and put down another course of bricks using "Soaps" or Stock brick right around the perimeter (and internals) of the house, say using stock brick, that would raise you up approx 3" that would just about meet the regs. but that's a lot of work but i'm afraid it's got to be done:(

Get the brickies back ASAP and let the house settle for a week or so
cause there's no drying at the moment whilst at the same time do the necessary ground works i.e. insulation, mesh radon sump etc are all okay

Don't forget to check all the corners of the house with a laser ensuring all the levels are okay

What are your site levels like? have you stayed high or low or exact as
per your planning permission? if you stayed a little low no problem, personally i wouldn't worry about raising your floor 3" unless your house at the moment is really high

I know what you're going through and it's a complete nightmare a this stage
but it just means a delay of a week or so and it'll be worth it.

maybe muffler, dolanbaker, kadman mellor and the others could help you out on this one afterall they're qualified

hope this helps, the house building manual is really an invaluable tool

De_man

by the way i forgot, if you ring your concrete supplier first thing on
monday to cancel say 7am or even earlier (some of them start at 630)

you should be okay.

De_man

De_man wrote:

i'm afraid you've a huge problem there, you don't have enough (unless your engineer is willing to chance it) i reckon the slab would crack when you put the blocks on it:eek: sorry but it's a non starter!!!

The regs state on page 42 of the house building manual (47 Yoyo available from easons on O Connell Street) state "150mm min thickness for ground supported concrete floor"

I would agree with you there, also the book also states that all block wall load bearing or otherwise need to have their own seperate foundation.

Non load bearing timber stud partitions are OK, thats what I am using, but I put in extra steel mesh just to be sure.

De_man wrote:

2. consulting your engineer or brickie, i'd go for the most sensible option
and put down another course of bricks using "Soaps" or Stock brick right around the perimeter (and internals) of the house, say using stock brick, that would raise you up approx 3" that would just about meet the regs. but that's a lot of work but i'm afraid it's got to be done:(

Good idea, This is what I would do in this situation, just be aware of any total height restrictions on the planning. One word of warning! with raised walls you will need to add some bracing before pouring, as the wet concrete will try to push these wall out & over.

De_man wrote:

I know what you're going through and it's a complete nightmare a this stage
but it just means a delay of a week or so and it'll be worth it.

maybe muffler, Deleted User, kadman mellor and the others could help you out on this one afterall they're qualified

hope this helps, the house building manual is really an invaluable tool

Thanks. I'm flattered but the only qualifications I have are in IT (Cisco, CCNP etc) Like yourselves, I have learnt a lot the hard way, but mainly by lurking on boards like this and yahoo UK_selfbuild forum, as well as a LOT of research into most aspects of building.

De_man

Deleted User wrote:

One word of warning! with raised walls you will need to add some bracing before pouring, as the wet concrete will try to push these wall out & over.

yep that's very true, i didn't think the problem over fully last night
imho, cause you'll be using soaps or stock brick, they'll never hold the concrete i reckon you might have to take the radon barrier back up - what a job if you've used the double sided tape :eek: then raise the walls, let settle, then put radon barrier, insulation etc etc back down.

alternatively, if you want to brace the walls 9X3's would be most suitable i reckon

Salmon, contact your engineer first thing in the morning, but don't pour the slab before you have approval.


all the best

Salmon

I just dropped down to the site this afternoon a little worried about the distance from the top of the insulation to the top of the block so I re-measured it! Turns out my calculations, measuring tape or maybe my memory was a little off! I measured it to be between 125mm and 160mm so im a lot happier today!!! I'm looking to pour tomorrow but the forecast isnt the best! I'm gonna have another look at the forecast and will decide later this eve whether or not we'll pour tomorrow! Thanks for the help so far folks, this really is a great resource to have for anyone self building!!!

De_man

Salmon wrote:

Turns out my calculations, measuring tape or maybe my memory was a little off! I measured it to be between 125mm and 160mm so im a lot happier today!!!

i know where you're coming from!!! that's grand just a quick suggestion regarding holding the insulation on the sides of the external walls in place. mix up a bit of concrete and every few feet or so put a bit down on the side of the insulation then put blocks on the top of the insulation (resting on the external walls), that should hold it in place for you. move them when doing the screed

best of luck with the weather, i've always found TV3
page 164 on the teletext very accurate.


let us know how you get on:D

Good luck tomorrow, hope the pour goes well for you.

Salmon

Ok Lads! The pour has been cancelled but re-ordered for first thing on wed morning. I now need to get some insulation boards to cut and place around the edge of the house! Am I better off getting the 25mm aeroboard or the 60mm xtratherm that I used so far? It might be a little easier to place the aeroboard but i'd imagine that the xtratherm stuff will perform much better! Any ideas which insulation is used for the edging?

De_man

i'd use the 60mm, it's also easier to put into position, use the concrete as i explained in a previous mail, plan your services now it'll be much easier for you in the long term, nothing worse having to chase floors later on.:(


just hope that the weather stays dry for you on wednesday

i too really need a dry week ...i'm weeks behind schedule....cause of the weather waiting waiting & waiting for the wind and rain to stop

fatchance

Hello all, first post!!

I left a gap of the width of the insulation around the edges and then jammed the edge insulation down into this gap so it would'nt move, worked a treat.

Dude, I know its the big pour tomorrow and no doubt the heart is in the mouth, especially as you seem to be doing it yourself, but if I were you I would hold off on the pour till you are sure you get a dry spell. Trust me, nothing is as demoralising as a concrete floor just poured and the rain starts spilling. In the scheme if things another week is not going to make a hell of a lot of difference to the job overall. I know you are anxious to make progress but down the line some roofer will no doubt hold you up a month or so! Relax and wait for a definate good spell. Just my 0.02$ Good luck

De_man

fatchance wrote:

Hello all, first post!!

I left a gap of the width of the insulation around the edges and then jammed the edge insulation down into this gap so it would'nt move, worked a treat.

Dude, I know its the big pour tomorrow and no doubt the heart is in the mouth, especially as you seem to be doing it yourself, but if I were you I would hold off on the pour till you are sure you get a dry spell.

Fatchance I fully agree, thats exactly the way i did my edge insulation, it certainly makes life easier.

I wonder how salmons floor went? the weather was fine earlier in the day
but as the day went on......:eek:

fatchance

So Dude ____________how Did The Pour Go?????????????????

Salmon

It didnt go too bad!! I'll up some pics at the weekend!! We were due to start early on wed morn (8:30), but the concrete crowd rang me to inform me that 'one of our trucks is broken down and is in the way of all the others!' anyhow it started at around 10:30. Glorious weather when putting in the concrete, the insulation went in around the edges as I requested and everything went well. Except! Because all the concrete wasnt in until around 1:30 it wasnt too dry so we powerfloated it at 10:00 wed night and again on thur morn at around 5am (very early I know!!). I havent seen it yet since but im told its not too bad, not as good a surface as it would have had if it hadnt rained but sure hey its all gonna be covered over anyway eventually!!

Thanks again for all the suggestions and help and I'll probably have more questions to ask in the coming weeks!! (Pics to follow!!!!)

Salmon

Hi All! Just posting up a pic of the finished floor for anyone interested! It doesnt look too bad considering the weather we had that night but the main thing is that the floor is level! Looking forward to getting the blocks up in the next few weeks and i'll be back for more advice later on!!!!

Pic of finished floor: http://picasaweb.google.co.uk/paul.uineill/House/photo#5020590367156937554