Insulated Plasterboard - Sealing + attaching

yop

Hi
I am insulating the upstairs of the garage I am building as I am using it for an office space.
The shed is a block and a half, so upstairs has about 2 blocks and then the ceilings on the widths and then the unplastered block gables.

I am planning on using 38mm insulated plasterboard on all walls and ceilings.
So I think I will be using the fixings for attaching the blocks, not unless there is a better option, but of the ceilings I am at a bit of a loss as how to attach them.

I will have 2 fluoresant lights hanging out of the ceiling so what do I use to hold these in place?

Same for sockets and light switches, since the plasterboard and insulation is 38mm thick do I just cut out a track out of the plasterboard and run the cables down and attach the sockets/switches?

Sorry for all the questions

Thanks

Also, to make it air tights as possible, what would you suggest I do before I put up the plasterboard, do I use a membrane of some sort?

mp22

Dot and dab can-be used on the block wall.The adhesive is aprox 5 or 6 euros a bag (25 kg).

Ceiling use 50mm * 4 or 4.5 screws with 6" spacing.
Cutting tracks in the insulation for wires is the way to go (IMO)
fluorescent lights use longer screws.

yop

Thanks very much for that.
Is that a special adhesive for the dot and dab?

Spot on re the screws, are they the plasterboard screws though or just standard screws?

Where the 1.5 blocks rise up into the office upstairs, the wall plate is sitting on this and then the rafters on the wall plate. The wall plate obviously isn't flush with the inside of the block, so to support the top of the plasterboard should I build from the top of the block to the bottom of the rafter up? Does that make sense?
I can take a picture if it makes more sense.

Thanks very much

mp22

Standard screws.Any builders suppliers will have the adhesive.

Normally you will board the ceiling first.
If you cut timber pieces that sit on the top of the wall and are screwed into the rafters,(one end cut square other end cut at the roof pitch)this will support the top of the board.

Carlow52

Plasterboard screws, not std ones as they rust.

38 all in very thin, hardly worth it:)

fix a batten between ceiling rafters to catch the lights


Cutting groves in insulation is the wrong way to do this

Am not clear on the layout here but for an office I would use external trunking with bottom of it 80cm from floor- desk will fit under it
Can have lan. fone.sockets, bla bla all there and one master switch at the end near the door to say goodnight:)

makita

Anytime we used insulated slab we always ran the wire through conduit as the insulation can eat into the wires over time

yop

Thanks lads,
38mm is too thin? You sure about that? What do you suggest?

The lights will be on the collar ties, so I presume that I put in a bridge between the collar ties for the lights.
Its a 2 desk office space for myself and MAYBE a temp. Trunking would be expensive wouldn't it?
Would the trunking in the insulation/plasterboard do or is that still a no no?

Carlow52

re the thikness when u consider the cost of fitting and skimming it etc the extra material cost is not significant.

I would go 50mm on 12.5 mm pb:)

Correct re collar bridge, just remember where it is.

You dont need trunking all around, say a 3m length.

Again if you consider the ease of fitting it externally on the pb as opposed to all the cutting out etc which screws the the insulation/cold bridging/airtightness etc..

yop

Carlow52 wrote: »

re the thikness when u consider the cost of fitting and skimming it etc the extra material cost is not significant.

I would go 50mm on 12.5 mm pb:)

Correct re collar bridge, just remember where it is.

You dont need trunking all around, say a 3m length.

Again if you consider the ease of fitting it externally on the pb as opposed to all the cutting out etc which screws the the insulation/cold bridging/airtightness etc..

I know what you are saying, its about 1 euro extra for the 50mm.

Wonder how much that trunking is? It would be "pee" easy to install for sure.

Any opinion on sealing the edges for air tight?

Carlow52

sealing the edges of the composite boards can be a pain, either the insulation is 2 big or 2 small?

I dont use the composite any more, I fix and tape the edges of the insulation and then fix the pb separately and stagger the joints from the insulation joints.

In addition I have moved on to wood fibre boards with T + G edges.

It really depends what standard of work you want to end up with, bearing in mind budget.

are the concrete block gables cavity wall or cavity block or solid?

yop

Carlow52 wrote: »

sealing the edges of the composite boards can be a pain, either the insulation is 2 big or 2 small?

I dont use the composite any more, I fix and tape the edges of the insulation and then fix the pb separately and stagger the joints from the insulation joints.

In addition I have moved on to wood fibre boards with T + G edges.

It really depends what standard of work you want to end up with, bearing in mind budget.

are the concrete block gables cavity wall or cavity block or solid?

Its a cavity block wall.

Is your solution not more expensive and time consuming?

I am on a budget for sure, but I am not going to skimp 100 euro to get a better solution.

Carlow52

yop wrote: »

Its a cavity block wall.

Is your solution not more expensive and time consuming?

I am on a budget for sure, but I am not going to skimp 100 euro to get a better solution.

Slab and dabbing the gables then will work.

If you research the properties of the wood fibre u will see that their thermal performance in roofs is vastly superior to the 'kingspan type'

Cant comment on pricing or time as to do so would start the discussion:
do you want a cheaper faster job that is a bad solution, even if within budget

yop

Re the fixings for these, I have the slab screws (90mm) and the mushroom washers, but how far in do the washers go? should they be a few mm into the slab or are are the flush?

Anyone install these slabs onto timber using this method?

Carlow52

yop wrote: »

Re the fixings for these, I have the slab screws (90mm) and the mushroom washers, but how far in do the washers go? should they be a few mm into the slab or are are the flush?

Anyone install these slabs onto timber using this method?

Is this not done yet:D I thought we'd have the Xmas party there

The heads of the mushroom fixings should be just below the surface so as u get a bind on them with the skim. Having said that I have seen them buried and then bonding used to fill the hole before skimming

use the screws for the timber/ mushi's for concrete

yop

lol, Its a 1 man show doing it all I am slow I admit!

I have the block walls done, I put them below the surface a little as I am not skimming the walls so I will just fill them.

The timber ones aren't going is a well though, I thought they maybe put into the board a bit but thats not the case, they way they are now will leave a hump