Mushroom Fixings - How Many for an 8 x 4 Sheet?

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So I'm insulating the kitchen with 63mm overall, insulated plasterboard. Kingspan recommended using 18 fixings per board and this is how many I used for attaching the first board. However it seems OTT. Looking at what other people suggest online, I've seen anything ranging from 6 per board to 12.
So how many do you reckon? The fixings are 110 mm going into 9" cavities. Also when I hammer the heads just below the surface, does it matter if the paper tears? It's easy to get the central part of a head a few mm below the surface, but it dishes with the edges flush and trying to get these recessed is what causes the tears. Do I need to use tape over the heads? I'm not going to skim the board, just paint over, so tape could be hard to cover.
 
Just discovered a short piece of brush handle makes an ideal punch for driving heads below surface. The right diameter too and less likely to tear paper.
 

johniosaif

Private Member
So I'm insulating the kitchen with 63mm overall, insulated plasterboard. Kingspan recommended using 18 fixings per board and this is how many I used for attaching the first board. However it seems OTT. Looking at what other people suggest online, I've seen anything ranging from 6 per board to 12.
So how many do you reckon? The fixings are 110 mm going into 9" cavities. Also when I hammer the heads just below the surface, does it matter if the paper tears? It's easy to get the central part of a head a few mm below the surface, but it dishes with the edges flush and trying to get these recessed is what causes the tears. Do I need to use tape over the heads? I'm not going to skim the board, just paint over, so tape could be hard to cover.
Why not use adhesive ?
 

raggles

Private Member
If you are using kingspan kooltherm boards and you are sticking then with adhesive all you need to fit are two fixings per board on opposite tapers approx 1200 mm from floor. I have used them quite a few times and if you actually take a look at kingspans how to video it explains it all very clearly. Oh and your welcome
 

Irish John

Active Member
So I'm insulating the kitchen with 63mm overall, insulated plasterboard. Kingspan recommended using 18 fixings per board and this is how many I used for attaching the first board. However it seems OTT. Looking at what other people suggest online, I've seen anything ranging from 6 per board to 12.
So how many do you reckon? The fixings are 110 mm going into 9" cavities. Also when I hammer the heads just below the surface, does it matter if the paper tears? It's easy to get the central part of a head a few mm below the surface, but it dishes with the edges flush and trying to get these recessed is what causes the tears. Do I need to use tape over the heads? I'm not going to skim the board, just paint over, so tape could be hard to cover.
Hi Eugene by the way your explaining this is I guess your in Ireland.
The insulated plaster board you are using usually gets around 12 fixings per sheet.
There are two commonly used plugs one is a steel one and the other is plastic.
Yes if you tear the paper it weakens the hold.on the board.
Have never seen these boards put up and not been plastered. Usually the fixings are covered with scrim and ideally the wall receives a light coat of bonding with is straightened and floated with a float with nails. Skimmed when the bonding has dried enough.
 
Hi Eugene by the way your explaining this is I guess your in Ireland.
The insulated plaster board you are using usually gets around 12 fixings per sheet.
There are two commonly used plugs one is a steel one and the other is plastic.
Yes if you tear the paper it weakens the hold.on the board.
Have never seen these boards put up and not been plastered. Usually the fixings are covered with scrim and ideally the wall receives a light coat of bonding with is straightened and floated with a float with nails. Skimmed when the bonding has dried enough.

Yes I'm fixing directly to the wall without bonding adhesive. I used plasterboard for an attic room years ago and painted without skimming and it turned out fine. I read that it's recommended, if the boards aren't skimmed, to use a base coat of 10% emulsion (90% water) before painting to seal the board (or use a PVA sealant).
 
If you are using kingspan kooltherm boards and you are sticking then with adhesive all you need to fit are two fixings per board on opposite tapers approx 1200 mm from floor. I have used them quite a few times and if you actually take a look at kingspans how to video it explains it all very clearly. Oh and your welcome
Thanks Raggles!
Kingspan recommended 18 fixings and then I asked them would 15 be okay and they sort of hmmed and hawed but said it would probably be ok. So I wonder could I push it down to 12? I read on another forum that someone had problems fixing to 9 inch cavities, but maybe they were unlucky enough to end up driving through joints in the blockwork, or used too big a bit. When I drove in the fixings, they went in tight.
 

Irish John

Active Member
Yes I'm fixing directly to the wall without bonding adhesive. I used plasterboard for an attic room years ago and painted without skimming and it turned out fine. I read that it's recommended, if the boards aren't skimmed, to use a base coat of 10% emulsion (90% water) before painting to seal the board (or use a PVA sealant).
Yea bonding adhesive isn't much good on these insulated boards anyways for fixing them as it just don't bond right with the insulation
Remember what you done in the attic years ago was on an attic room not your kitchen that you'll be using and looking at regularly.
The fixings will stand out a lot in comparison to the screws or nails you used before. If tiling any of it you will need to fill the joints and smooth over the plugs.
 
Yea bonding adhesive isn't much good on these insulated boards anyways for fixing them as it just don't bond right with the insulation
Remember what you done in the attic years ago was on an attic room not your kitchen that you'll be using and looking at regularly.
The fixings will stand out a lot in comparison to the screws or nails you used before. If tiling any of it you will need to fill the joints and smooth over the plugs.
That's why I'm trying to get the edges of the mushroom heads even a mm below the surface. It's easy to get the central area well below. With a little care and practice and using that piece of brush handle, I think I'll be able to go around the perimeter of the head and recess it slightly. Two coats of paint maybe will fill in any hairline cracks where the fill plaster meets the board at the perimeter of the head.
Just thinking, maybe I could use caulking to fill the head depressions? Wouldn't it bond better than plaster to the fixings (which are metal)?
 

Irish John

Active Member
That's why I'm trying to get the edges of the mushroom heads even a mm below the surface. It's easy to get the central area well below. With a little care and practice and using that piece of brush handle, I think I'll be able to go around the perimeter of the head and recess it slightly. Two coats of paint maybe will fill in any hairline cracks where the fill plaster meets the board at the perimeter of the head.
Just thinking, maybe I could use caulking to fill the head depressions? Wouldn't it bond better than plaster to the fixings (which are metal)?
If you break the paper you compromise the slab and allow movement. Done properly you shouldn't have any hair line cracks.
Sure you can disguise a lot of stuff with paint and caultimately but that's not how it should be done.
Your house your choice but not my cup of tea.
 

Irish John

Active Member
If you break the paper you compromise the slab and allow movement. Done properly you shouldn't have any hair line cracks.
Sure you can disguise a lot of stuff with paint and caultimately but that's not how it should be done.
Your house your choice but not my cup of tea.
Above was meant to read caulk not caultimately. Damn autocorrect
 

tcd

Active Member
Caulk is usually used for internal corners on walls and or ceilings, around coving, cornice, architraves door facings, and skirting boards, if used on flat surfaces then there is a good chance it will flash when painted, if you don't want to plaster or, ames tape, your best bet would be some sort of filler, polyfill or equivalent product to cover any dents made,
 
Caulk is usually used for internal corners on walls and or ceilings, around coving, cornice, architraves door facings, and skirting boards, if used on flat surfaces then there is a good chance it will flash when painted, if you don't want to plaster or, ames tape, your best bet would be some sort of filler, polyfill or equivalent product to cover any dents made,
Is there such a think as a filler gun that filler can be put into (like a cake icing set)?
 
I was speaking to a plasterer today and also Kingspan. Plasterer recommended sealing central core of steel mushrooms with expanding foam to stop any moist air from inside cavities hitting the back of the filler covering the mushroom heads and causing damp spots. He said he's seen this happening. Kingspan said this isn't true and damp spots on walls are likely due to thermal bridging and moisture condensing on the cold surface of the plaster/filler covering the mushroom. Maybe it's a combination of both, but is there a thermally insulating filler to cover the heads that I could use to eliminate this? Or is it really a problem?

Second question: A gap of 5 mm between the bottom of the sheet and floor is recommended in Kingspan's installation guide. Is this too small? They recommend 15 mm elsewhere, but maybe it depends on the fixing method.
 

zombie

Private Member
Mate seriously just do all the boardwork and then pay a spread for a day and supply the materials.. .

It really ain't going to cost the earth and will be a proper job.

Everything else your suggesting imo is just going to look crap.

Ok for a garage or summet but not your kitchen!
 

Pagey

Private Member
I'm fixing direct to the wall. Plasterer said 12, Kingspan recommended 18.
The amount your spending on plugs would of got you a couple of bags of adhesive and just plugged in the middle you are taking two different opinions and don’t know whether your coming or going ask for advice on here it’s given and you still stick to what you “think” is best
 

Nicm

Well-Known Member
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Use the thermal plugs for peace of mind,or if using the metal one stick them into a waste piece of insulated board which fills them up before hammering in.And there’s more,spray them with a primer like it says on the bag to prevent black spots.Now there’s two great tips for you from a fellow Kildare man.If it was my kitchen i’d Skim it.
 
View attachment 20259 Use the thermal plugs for peace of mind,or if using the metal one stick them into a waste piece of insulated board which fills them up before hammering in.And there’s more,spray them with a primer like it says on the bag to prevent black spots.Now there’s two great tips for you from a fellow Kildare man.If it was my kitchen i’d Skim it.

Any particular primer? Maybe red oxide metal primer? I've seen it mentioned elsewhere that black patches could be caused by emulsion paint soaking through skim and reacting with the metal heads producing a black oxide.
 

Nicm

Well-Known Member
Any particular primer? Maybe red oxide metal primer? I've seen it mentioned elsewhere that black patches could be caused by emulsion paint soaking through skim and reacting with the metal heads producing a black oxide.
Should do it.
 
Do I need to remove vinyl wall paper before slabbing? Kingspan say at least score the paper if dabbing or try and get top layer off, but I wonder should I try to strip it back to the paint underneath or even sand back to the original skim?
 

Pagey

Private Member
The plugs on therma board are for fire regs and for if there is a fire the board will break down in a certain way same to studs them holes in metal studs are not for services to go through they are designed for in a fire and at high heat them don’t just collapse and sort of break down
 

McPlaster

Private Member
That's why I'm trying to get the edges of the mushroom heads even a mm below the surface. It's easy to get the central area well below. With a little care and practice and using that piece of brush handle, I think I'll be able to go around the perimeter of the head and recess it slightly. Two coats of paint maybe will fill in any hairline cracks where the fill plaster meets the board at the perimeter of the head.
Just thinking, maybe I could use caulking to fill the head depressions? Wouldn't it bond better than plaster to the fixings (which are metal)?
Hammer a few long nails in the fecking things, near enough!
 
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