Insulated plasterboard and mushrooms

whiteshadow

a plasterer was booked to do this for me but pulled out of the job.

I've got to insulate a room
I've got 13 sheets of 8x4 insulated plasterboard, 1 1/4 inch thick
I've got a box of mushroom fittings

Ive got no idea how to fix them to walls and ceiling


Can anyone give me any pointers?
thanks

bertie1

You will have to screw them to the ceiling , on the walls an adhesive mixture is normally used & then drill in the mushrooms with a masonary bit & hammer home.

northdublin

i used that type of fixing in all the rooms but i fixed the plaster board directly to the wall. they use an 8 mm masonary bit and when drilling if posible go about an inch deeper than the dept of the fixing as they tend to push dust forward of the tip of the fixing reducing the dept of the hole. i would use a good sds drill and a hoover to catch as much dust as u can as there is a lot of drilling involved. when doing it here i hit the head of the fixing untill its just below the surface of the board the i scrim taped all the heads and joints. dont worry about the dent created by the head whats important is the board is fixed propperly and doesnt move especially around the joints

whiteshadow

hi what sort of adhesive mixture ? and what sort of screws would i use?

B1977

I m putting up insulated board aswell.was told to use gyproc compound adhesive.
where do you get those mushroom bolts

B1977

i am putting up plasterboard with insulation attached,any ideas how i can cut these boards to size,was also told to leave 15mm gap between floor and end of plasterboard

whiteshadow

B1977 wrote: »

I m putting up insulated board aswell.was told to use gyproc compound adhesive.
where do you get those mushroom bolts

i got the mushroom bolts in the builders providers.
just ask for mushrooms and they'll know what you mean.
thanks for tip re the adhesive

hjsimpson

The adhesive i've used is Gypsum bonding compound with pva (not ordinary bonding)
The slab is stuck to the wall wit dabs of this and secured with "mushrooms"...or insulation fixings
They are available in 50,70,90,110 mm lens (and longer) in plastic and steel.
Some plasterers dont like the steel ones....catches the trowel.
I would say u need 70 mm plastic ones and a good 8mm drill.

northdublin

B1977 wrote: »

i am putting up plasterboard with insulation attached,any ideas how i can cut these boards to size,was also told to leave 15mm gap between floor and end of plasterboard

i used a standard saw to cut them,along with a chalk line. you also need the 90 mm mushrooms and an 8mm bit if using the insulated board.and use a piece of timber to rest the board on while fixing then slide it out leaving the gap underneath.

stick-dan

Ok i work in a hardware/building suppliers so here's the heads up.

"Mushrooms"

These are actually called cavity poly fixings and come in either 80mm, 90mm or 110mm lengths. Proceed to you're local DIY and they will advice you on which to use. You say you're using insulated plasterboard known as themalboard so the odds are it is 29mm thick or 38mm thick in which case if it is the later the better fixing to go for is the 90mm or the 110mm.

To plug in these fixings you will need and SDS drill and what i believe is an 8mm SDS bit but don't quote me on the size as i'm not certain. Be sure to not buy the cheap bit. Paying that bit extra will allow you to drill easier and also make for a cleaner bore!

The bonding compound is available in all good building suppliers. A nice clean layer will suffice for good adhesion. Make sure you get bonding compound and not gypsum bonding as they serve two different purposes. Make it clear the job you are undertaking when buying.

ircoha

B1977 wrote: »

i am putting up plasterboard with insulation attached,any ideas how i can cut these boards to size,was also told to leave 15mm gap between floor and end of plasterboard

Why the gap, with the whole drive toward air-tightness?

newmills

Hi,

My mate just got the same job done to his garage walls. I could get the number of the guy that did it for him and pm it to you. He might have some more advice or he may be able to do it. Hope this helps.

John Mason

newmills wrote: »

Hi,

My mate just got the same job done to his garage walls. I could get the number of the guy that did it for him and pm it to you. He might have some more advice or he may be able to do it. Hope this helps.

hi can you pm me the details too. i have a kitchen and a bathroom that needs doing

newmills

irishbird wrote: »

hi can you pm me the details too. i have a kitchen and a bathroom that needs doing

Hi, sent it to you as required

hiscan

if your dabbing make sure you dab a full line across the top and bottom of the board if your looking for air tightness, id recommend drilling the slab directly onto the wall its a much better job plus i always use the new metal fixings its a much better job especially in the case of fire regs

B1977

ircoha wrote: »

Why the gap, with the whole drive toward air-tightness?

should i leave a 15mm gap,these boards have 50mm insulation,what would the recommended length of screw be?

championc

Hi all

I'm resurecting this old thread since I was planning to redecorate my hall, stairs and landing. I have a Semi detatched and so this is a fairly reasonable wall surface which is an outside gable end wall so reckon it's worth doing.

If I use the mushroom fixings, do I still need the bonding compound ? How many mushroom fixings do you use for each 8 x 4 sheet (maybe less fixings and more compound ) ? Is compound for attaching the boards to the wall, and if so, what are the mushrooms doing ?

Or for this gable wall, would I just be better considering external wall insulation ?


C

mad m

championc wrote: »

Hi all

I'm resurecting this old thread since I was planning to redecorate my hall, stairs and landing. I have a Semi detatched and so this is a fairly reasonable wall surface which is an outside gable end wall so reckon it's worth doing.

If I use the mushroom fixings, do I still need the bonding compound ? How many mushroom fixings do you use for each 8 x 4 sheet (maybe less fixings and more compound ) ? Is compound for attaching the boards to the wall, and if so, what are the mushrooms doing ?
Or for this gable wall, would I just be better considering external wall insulation ?


C

Its 12 mushrooms fixings to one board (Recommended)....Never used any compond to fix these to the walls.

How old is your house?

championc

1972 - so it's cavity blocks built so it's insulation on either the inside or outside of the wall


C

nophd08

mad m wrote: »

Its 12 mushrooms fixings to one board (Recommended)....Never used any compond to fix these to the walls.

How old is your house?

12 fixings per board...............Recommended by who?

smoochie06

championc wrote: »

Hi all

I'm resurecting this old thread since I was planning to redecorate my hall, stairs and landing. I have a Semi detatched and so this is a fairly reasonable wall surface which is an outside gable end wall so reckon it's worth doing.

If I use the mushroom fixings, do I still need the bonding compound ? How many mushroom fixings do you use for each 8 x 4 sheet (maybe less fixings and more compound ) ? Is compound for attaching the boards to the wall, and if so, what are the mushrooms doing ?

Or for this gable wall, would I just be better considering external wall insulation ?


C

http://www.xtratherm.com/wallsolutions/wallindex.php

This is the website i used for my DIY job. I used 8 mushroom fixings. Two of these need to be galvanised steel for fire regulations iirc. I didnt use compound i just fixed them directly to the wall with the mushrooms.

That link gives you a short video of what you need to do and i found it very helpful. Hope it helps you.

CBYR1983

I had a hall stairs and landing done a few weeks ago. Also did gable end of box room.

Make sure you have enough depth if the staircase runs along the wall. I put a thin half d-shaped piece of architrave along the string of the wall, roughly 40mm depth, maybe 12mm thick. Otherwise the boards would have protruded nastily over the wall string, which was only giving me about 20mm from the wall.

Then I used 38mm warmboards. It looks neat.

There's a window on the gable wall of my house as well, thankfully the windowboard had ample depth and the reveals were plastered.

Loads of dust from the drilling though - be prepared.

Well worth doing though. Have a think about other walls while you're at it, even though it's awkward to take off rads and that at this time of year. I bought the stuff from "U-Value".

bobbuilder

Hi im a plasterer by trade warm boards are stuck to walls or they are fixed not stuck and then fixed your wasting money and time doing that

championc

CBYR1983 wrote: »

I had a hall stairs and landing done a few weeks ago. Also did gable end of box room.

Make sure you have enough depth if the staircase runs along the wall. I put a thin half d-shaped piece of architrave along the string of the wall, roughly 40mm depth, maybe 12mm thick. Otherwise the boards would have protruded nastily over the wall string, which was only giving me about 20mm from the wall.

Then I used 38mm warmboards. It looks neat.

There's a window on the gable wall of my house as well, thankfully the windowboard had ample depth and the reveals were plastered.

Loads of dust from the drilling though - be prepared.

Well worth doing though. Have a think about other walls while you're at it, even though it's awkward to take off rads and that at this time of year. I bought the stuff from "U-Value".

Sounds like it was good timing on your part given the recent weather. Probably too early to tell the effectiveness - yes ?

paddy147

CBYR1983 wrote: »

I had a hall stairs and landing done a few weeks ago. Also did gable end of box room.

Make sure you have enough depth if the staircase runs along the wall. I put a thin half d-shaped piece of architrave along the string of the wall, roughly 40mm depth, maybe 12mm thick. Otherwise the boards would have protruded nastily over the wall string, which was only giving me about 20mm from the wall.

Then I used 38mm warmboards. It looks neat.

There's a window on the gable wall of my house as well, thankfully the windowboard had ample depth and the reveals were plastered.

Loads of dust from the drilling though - be prepared.

Well worth doing though. Have a think about other walls while you're at it, even though it's awkward to take off rads and that at this time of year. I bought the stuff from "U-Value".

Or you could just remove your entire staircase and landing and insulate completely.

What the hell was I thinking,at the time.:D

Buford T Justice

If a job's worth doing though..........

CBYR1983

paddy147 wrote: »

Or you could just remove your entire staircase and landing and insulate completely.

What the hell was I thinking,at the time.:D

Wow- that's some job you took on there! We're living in the house with a small child so that type of destruction wasn't an option - but i imagine your effectiveness is way higher. We did under the stairs too but obviously missed those spaces. What thickness did you use? Some job, fair play.

In fairness we do seem to be noticing the difference - the hall used to be an ice box and we even had condensation forming mould on the gable wall. Place was much cosier during the recent cold snap - happy to have done it, even if there was some hassle and inevitable redecoration. I like the idea of keeping the heat in rather than heating the walls. We're not there during the day, and external retro-fitted seems too messy, risky and awkward to me.

championc

I too don't particularly want to heat my walls. Does anyone know if 4" of outside insulation the same as 4" inside or would the equivalent be less ? I cannot really see myself installing more than about 40mm on the inside - and that would include the plasterboard too.

CBYR1983

Pics

handlemaster

CBYR1983 wrote: »

I had a hall stairs and landing done a few weeks ago. Also did gable end of box room.

Make sure you have enough depth if the staircase runs along the wall. I put a thin half d-shaped piece of architrave along the string of the wall, roughly 40mm depth, maybe 12mm thick. Otherwise the boards would have protruded nastily over the wall string, which was only giving me about 20mm from the wall.

Then I used 38mm warmboards. It looks neat.

There's a window on the gable wall of my house as well, thankfully the windowboard had ample depth and the reveals were plastered.

Loads of dust from the drilling though - be prepared.

Well worth doing though. Have a think about other walls while you're at it, even though it's awkward to take off rads and that at this time of year. I bought the stuff from "U-Value".

how wide was your stairs. mine is only 820. Purchased 38mm which would bring it below the 800 allowable

CBYR1983

Is that wall to wall? I have well over 800 when I take in above the banister. I never had that just on the treads.

handlemaster

CBYR1983 wrote: »

Is that wall to wall? I have well over 800 when I take in above the banister. I never had that just on the treads.

From the inside of the handle rail to the wall is 820 if the hand rail was taken off the out side the support there would be 850

CBYR1983

If you need to get a wheelchair up it fully open then I'd worry, otherwise for the vast majority the cold is more of an issue imho.

Unless you're planning on adding a stairmaster!

Sounds like your rail is screwed to the opposite wall? My is open on opposite side to gable, but with banister.

Grove85

I just did this job in my own house.
I got 50mm boards. Fixed them with 110mm mushrooms. Using an 8mm sds bit. Put a piece of electrical tape on the bit, a wee bit deeper than the depth of the mushroom. You don't want to go all the way into the cavity. Don't whack in the mushrooms all the way till you have most in. Then sink them just under the surface. Use about 9 for a 8x 4 sheet. Then consider using a filler and jointing tape over the mushrooms when filler still wet. Damping the tape a bit. The mushrooms can appear through paint if just skimmed over. I'm not a professional but this was my approach.

Geezy

Does anyone know how to remove these steel mushroom fittings? Presuming I need to drill them out with a metal bit?

ballystephen

Dot n Dabbed mine about 10 years ago . Still grand

EugenesDIYDen

I've seen some posts elsewhere from people that had staining problems on paint.
Has anyone come across this very often?
One theory is that it's due to thermal bridging when mushroom fixings are used and moisture condenses on the surface of plaster directly over the heads. The other theory is that paint soaking into the skim reacts with the metal of the fixings, creating an oxide/rust that then leaches to the surface. A plasterer advised me to prime the heads to stop this and use plastic caps to cover the heads.
Is there any sort of insulating filler that could be used to cover the depression over a mushroom head that would eliminate condensation?

listermint

EugenesDIYDen wrote: »

I've seen some posts elsewhere from people that had staining problems on paint.
Has anyone come across this very often?
One theory is that it's due to thermal bridging when mushroom fixings are used and moisture condenses on the surface of plaster directly over the heads. The other theory is that paint soaking into the skim reacts with the metal of the fixings, creating an oxide/rust that then leaches to the surface. A plasterer advised me to prime the heads to stop this and use plastic caps to cover the heads.
Is there any sort of insulating filler that could be used to cover the depression over a mushroom head that would eliminate condensation?

Advice with mushrooms is to spray them with antioxide paint prior to plastering.

dodzy

listermint wrote: »

Advice with mushrooms is to spray them with antioxide paint prior to plastering.

Just don't use the metal fixings. Go with the plastic variants.

bman1

I work in a hardware shop and all our current suppliers changed to metal a few years ago, can't get plastic now. That's not to say other suppliers aren't still doing them. We've been told by a good few tradesmen now that they use B.I.N primer for priming the heads of the fixings, and it's available in a spray can so they prefer that to going at each fixing with a paint brush. Now none of that is gospel but these fellas are at it years and tend to learn what works and doesn't work I suppose.

EugenesDIYDen

bman1 wrote: »

I work in a hardware shop and all our current suppliers changed to metal a few years ago, can't get plastic now. That's not to say other suppliers aren't still doing them. We've been told by a good few tradesmen now that they use B.I.N primer for priming the heads of the fixings, and it's available in a spray can so they prefer that to going at each fixing with a paint brush. Now none of that is gospel but these fellas are at it years and tend to learn what works and doesn't work I suppose.

What's B.I.N. and would red oxide primer work?
Is this staining thing really a common issue with plasterboard if there is good ventilation and no activities in a room that generate moisture such as drying clothes on radiators and cooking? The room is a kitchen, but unlike years ago there's no boiling on the cooker, mostly microwaving and short duration use of the oven. What do I fill over the mushroom heads with and could I use a non-expanding foam?

dodzy

EugenesDIYDen wrote: »

What's B.I.N. and would red oxide primer work?
Is this staining thing really a common issue with plasterboard if there is good ventilation and no activities in a room that generate moisture such as drying clothes on radiators and cooking? The room is a kitchen, but unlike years ago there's no boiling on the cooker, mostly microwaving and short duration use of the oven. What do I fill over the mushroom heads with and could I use a non-expanding foam?

this is B.I.N

https://www.woodies.ie/zinsser-500ml-bin-primer-seal-1112573?utm_source=google_shopping&gclid=EAIaIQobChMIiqSTq7TB1wIV7b_tCh0ZiApZEAQYASABEgKunvD_BwE

And the mushroom fixtures are flat headed and hammered home (into predrilled holes) fractionally below the plasterboard surface and then plastered over.

EugenesDIYDen

dodzy wrote: »

this is B.I.N



And the mushroom fixtures are flat headed and hammered home (into predrilled holes) fractionally below the plasterboard surface and then plastered over.

Is the idea of this stuff to prevent any staining from mildew or to stop any reaction products from emulsion paint and the metal head of the mushrooms leaching out through the plaster?

1983ish

I filled the metal fixings with normal silicone then put the caps on. Bout 2 years ago and no issues so far

EugenesDIYDen

1983ish wrote: »

I filled the metal fixings with normal silicone then put the caps on. Bout 2 years ago and no issues so far

Do the caps bring the heads above the surface? I'm barely recessing them and not going to skim. Didn't skim attic room plasterboard 25 years ago, just painted and still fine.

1983ish

Caps are only 2/3mm thick
Id say you’d have to sink them a bit then fill over the caps/fixings if your not plastering

EugenesDIYDen

1983ish wrote: »

Caps are only 2/3mm thick
Id say you’d have to sink them a bit then fill over the caps/fixings if your not plastering

Might be a little difficult without tearing the paper. It's the edges that are hard to recess without doing damage. I'm using a short piece of brush handle as a punch which works well. It's easy to go around the perimeter of the head and hammer down.

randombar

Re-Resurrecting an old one here.

Have a cavity block garage and had the insulation board for about 2 years for it. Do people recommend dabbing or mushrooming?

Also required tools? Apart from SDS drill and decent 8mm bit. Put a few ceiling board up yesterday. Discovered I need a tool belt to hold all the damn screws and hook the drill onto Guessing chalk line.

EugenesDIYDen

GaryCocs wrote: »

Re-Resurrecting an old one here.

Have a cavity block garage and had the insulation board for about 2 years for it. Do people recommend dabbing or mushrooming?

Also required tools? Apart from SDS drill and decent 8mm bit. Put a few ceiling board up yesterday. Discovered I need a tool belt to hold all the damn screws and hook the drill onto Guessing chalk line.

I finished insulating my kitchen last year. After hammering the mushrooms flat onto the board I used a short piece of brush handle (a few inches long) to recess the heads, painted over with red oxide and filled. Haven't had any issues with dark patches after giving the room two coats of Dulux kitchen paint.
Is your board bowed after being in storage? Bring it somewhere warm to let it dry out if that's the case. Mine was a bit bowed which caused issues then when I installed kitchen units (walls were probably not level/plumbed in any case).
As regards tools, unless you have a helper, you'll need something to prop against the boards while installing if you're using mushrooms until you get a few in. I used some shims of timber underneath to push the boards tight up against the ceiling, but that was really so that there were no gaps. If you have a 4 stone weight or something else heavy, you can prop a timber board against it and against the sheet to keep it in place. The 65mm stuff weighs about 30kg and is awkward and fragile.

EugenesDIYDen

Here's some images before a moderator removes them:
https://www.facebook.com/groups/203863340138801/permalink/295499120975222/

randombar

EugenesDIYDen wrote: »

I finished insulating my kitchen last year. After hammering the mushrooms flat onto the board I used a short piece of brush handle (a few inches long) to recess the heads, painted over with red oxide and filled. Haven't had any issues with dark patches after giving the room two coats of Dulux kitchen paint.

Did you skim after or paint?