watsonpj
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| posted on 28/6/10 at 08:32 PM |
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House floor insulation
I'm going to have the house extended and as I'm doing the complete heating system I thought I'd insulate the floor. I've had a
look around and there seems to be lots of expensive ways of doing it. I also found a few sites where people have suggested that a good and cheap way
is to use this
Image deleted by owner
type of fencing stapled to the bottom of the floor joists which hold up spaceblanket
Image deleted by owner
so it looks a bit like this
 
floor_ins
comments welcome. Its this a good method thats ok for condensation?
Pete
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tegwin
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| posted on 28/6/10 at 08:34 PM |
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Cunning idea... just an uneducated thought... dont you need some air flow between the joists to prevent condensation forming and thus rotting the
woodwork?
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Would the last person who leaves the country please switch off the lights and close the door!
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BenB
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| posted on 28/6/10 at 08:36 PM |
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It all depends how thick your insulation can be.... Rockwool type products are all well and good but you need quite a thickness compared to the foil
covered foam type insulation....
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watsonpj
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| posted on 28/6/10 at 08:38 PM |
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Thats why the bottoms of the joists are not covered as the fencing mesh is open allowin the wood to breath. That is my main concern which is why
I'm asking the question. I just know that the house is very cold in the winter and the heating can't keep up and neither can my bank
account 
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watsonpj
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| posted on 28/6/10 at 08:40 PM |
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I guess the 150 or the 200mm os space blanket which is rockwool in foil.
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zilspeed
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| posted on 28/6/10 at 08:42 PM |
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The name of the mesh you are looking for is Netlon.
When building from new, it is draped over the top of the joists with the insulation dropped inside.
You can still do it the way you suggest, but it'll be a James Hunt of a job.
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watsonpj
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| posted on 28/6/10 at 08:46 PM |
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I think it will still be easier and cheaper than pulling up all the floor and using cellotex or one of the other brands of board products.
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kj
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| posted on 28/6/10 at 08:54 PM |
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Depending on your joist depth just go for 100mm fibreglass supported by the net.
That is used on lots of new builds and cuts out a lot of noise too,or if you are lifting the floor boards drop it in, don't cover any down
lights below and watch for cables.
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watsonpj
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| posted on 28/6/10 at 08:59 PM |
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thanks guys looks like I'm going to be busy.
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Peteff
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| posted on 28/6/10 at 09:26 PM |
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Fasten some battens to the side of your joist and drop rigid insulation in sections to ledge on them or put some slats on them and use rockwool.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Canada EH!
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| posted on 28/6/10 at 09:57 PM |
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Over here were it gets a little cold we put batts under the floor between the joists then close it all in with 1 1/2"or 2" hard styrofoam
panels.
Mice and other small rodents like to build nests in unprotected fibreglass batts.
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v8kid
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| posted on 28/6/10 at 10:26 PM |
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Scottish mice must have sharper teeth (or less brains) - the little darlings chew up styrofoam to make nests here!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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snapper
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| posted on 29/6/10 at 04:12 AM |
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Check building regs, they are very specific on insulation
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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kj
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| posted on 29/6/10 at 06:43 AM |
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Why use Rockwool, new glassfibre has the same u-values slightly under for sound performance but is cheaper and easy to work with.
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Paul2010
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| posted on 29/6/10 at 07:02 AM |
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My neighbour did this , it worked really well. He used even cheaper garden netting used for sweet peas & strawberrys etc.
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jossey
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| posted on 29/6/10 at 08:01 AM |
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tri iso. all day.
best by far.
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big-vee-twin
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| posted on 29/6/10 at 08:36 AM |
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Most Building regulations officers don't usually accept Tri Iso.
Insulation and type now has to be calculated by an approved energy assessor using software called SAP unfortunately gone are the days where you just
put in a bit of rockwool, covered by part L energy efficiency in buildings.
So if you have to go for building regs approval, best to get their input first or you may be waisting your time.
Another thing to consider is the amount of glazing you have in the new extension if its more than 25% you open up another can of worms.
Duratec Engine is fitted, MS2 Extra V3 is assembled and tested, engine running, car now built. IVA passed 26/02/2016
http://www.triangleltd.com
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bartonp
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| posted on 29/6/10 at 09:10 AM |
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Most heat goes out the walls, windows & roof. Better returns investment there.
Thick carpet on floor to stop draughts,t hat's all.
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jossey
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| posted on 29/6/10 at 10:37 AM |
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tri iso and building regs.
Because of the high U values it shoudl pass with private inspectors. the council ones generally have different requirements outside of building
regs.
i past using tri iso in the roof of my large loft conversion. all i used was tri iso on roof and kingspan 50mm in the space between the boards and the
25mm gap to the roof.
and in the floors and in the walls.
had no issues at all and its always warm in the winter with no heating in the loft at all.
its 7.6m x 6.2 m loft convertion and full tri iso all way round. solar glass helps keep it warm but its always ok without any heating.
quote:
Originally posted by big-vee-twin
Most Building regulations officers don't usually accept Tri Iso.
Insulation and type now has to be calculated by an approved energy assessor using software called SAP unfortunately gone are the days where you just
put in a bit of rockwool, covered by part L energy efficiency in buildings.
So if you have to go for building regs approval, best to get their input first or you may be waisting your time.
Another thing to consider is the amount of glazing you have in the new extension if its more than 25% you open up another can of worms.
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coozer
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| posted on 29/6/10 at 10:55 AM |
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Building regs specified 100mm of Kingspan (or celetex) in my loft extension. In the roof and in the walls.
They also specified 150mm of rockwool between the 9" ceiling joists.
It looks an expensive outlay but upstairs now we hardly need to put the heating on. All the rad thermo's are on No1. Well worth the initial
outlay IMO.
This coming winter I plan to have a log burner in that will reduce the need for the central heating even further!
LG,
Steve
1972 V8 Jago
1980 Z750
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big-vee-twin
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| posted on 29/6/10 at 11:16 AM |
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There is no doubt Tri Iso is good but unfotunately the testing methods used by the manufacturer doesnt strictly comply with the BS which is why a lot
of Building Control guys private and Council do not accept it, it has to be said the building regs it allows the discretion of the individual officer
to decide.
Thats why you need to consult the building control and then maybe hire an accredited energy assessor like me.
Duratec Engine is fitted, MS2 Extra V3 is assembled and tested, engine running, car now built. IVA passed 26/02/2016
http://www.triangleltd.com
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nick205
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| posted on 29/6/10 at 11:36 AM |
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Not sure from your OP, but are you talking about the ground floor floor or the first floor floor here?
When we extended (single storey) and added a conservatory the building regs/inspector specified the Kingspan type board in the ground floor floor and
walls and rockwool in the ceiling.
I went to town elsewhere and upped the rock wool loft insulation from 100 to 250mm. This made a big difference last winter to the heating demands.
It hasn't helped to keep the place any cooler in the recent warm weather though.
If it wasn't such as PITA I'd really like to add some insulation between the ground and first floor as well to cut the sound down.
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