Garage Conversion - Walls, Ceiling and Floor

[dotnetdave]

ok after reading lots and get some advice on here i have come the following plan of action.

Step 1 - Walls
1) Cover walls in DPM sheets temporary fixed with a batten at the top and batten (25x50) running along floor.
3) Place Xtratherm 50mm boards on to the wall wedging between the upper and lower battens and cover all joints with foil tape.
4) Fix vertical 25x50 battens over the insulation board fixing through the board with 100mm frame fixings on 400mm centres.
5) Fix 12.5mm plaster board to the battens therby leaving a 25mm gap betwen the insulation and plasterboard which i can drop wiring through for sockets.
6) Tape all joints, internal corners and external corners.

I have spoke to Xtratherm about this method and they have said placing the battens on top of the board or against the wall makes no difference.

Step 2 - Ceiling
1) Fix plasterboard to ceiling which will be lower than the side walls
2) Fit loft insulation between rafters.
3) Tape all joints

Step 3 - Floor
1) Cover floor with DPM sheets taping any joins and lapping up the walls 300mm (This will partially be done when fitting the walls so the floor DPM goes over the wall DPM)
2) Cover the floor in 75mm polystyrene sheet leaving a small gap around the edges.
3) Lay 18mm WPB plywood over the insulation (should i glue the edges) this again will leave a small gap around the edges.
4) Lay laminate underlay fibre boards and finally the laminate.

Would love anybodys comments on this plan whether good or bad

Thanks
Dave

 

[PrenticeBoyofDerry]

Board out the ceiling before you board your wall out.
Stagger joints in ceiling joints
put thin coat angle beads on external corners.
It would best to plaster finish the boards than to joint tape, will leave a better finish that is more hard waring.
If the garage conversion is being overseen by building controls get the electrical installation within that application.
The chances are that the electrical work will be notifiable;
//www.diynot.com/wiki/electrics:part_p
Also make sure the electrics are designed correctly taking in to consideration load, route of cables, method of installation etc..

 

[dotnetdave]

Board out the ceiling before you board your wall out.
Stagger joints in ceiling joints
put thin coat angle beads on external corners.
It would best to plaster finish the boards than to joint tape, will leave a better finish that is more hard waring.

would would you recommend doing the ceiling first ? if i do this it means the plasterboard on the ceiling is going to be butted up to the naked brick wall doesnt it ?

i was going to use corner joint tape on the only 2 external corners, the tape that has 2 metal strips inside it. No need for a plaster finish as its just a man room to get away and chill in lol so just going to tape joints, corners and screw heads and the a lick of paint.

 

[PrenticeBoyofDerry]

by boarding out the ceiling first, the wall boards will give added support to the perimeter edge of the ceiling.
It will make it easier to get a neater joint between ceiling and wall board too.
I understand you don't want the board up against the bare wall, but if you are battening out and insulating first this wont happen.

Joint taped walls can become shabby very quickly in comparison to a plastered wall. They will also leave a shadow on your paint work at the joints, if you are a novice tape jointer, even ones that claim to have experience at joint taping struggle to give it a professional finish!
If you want a finish that will offer better quality and longevity for very little cost difference, plastering is your best option
I would go for plaster all the time.
Your external corners, you will find that the steel thin coat beads much easier to fix, the too are more durable and want damaged when applying your coats.
The cost of a roll of flex corner tape and adhesive, compared to two lengths of thin coat bead?
And to say it is just a man room, if your missus is anything like mine your heading for a fall

 

[dotnetdave]

by boarding out the ceiling first, the wall boards will give added support to the perimeter edge of the ceiling.
It will make it easier to get a neater joint between ceiling and wall board too.
I understand you don't want the board up against the bare wall, but if you are battening out and insulating first this wont happen.

Joint taped walls can become shabby very quickly in comparison to a plastered wall. They will also leave a shadow on your paint work at the joints, if you are a novice tape jointer, even ones that claim to have experience at joint taping struggle to give it a professional finish!
If you want a finish that will offer better quality and longevity for very little cost difference, plastering is your best option
I would go for plaster all the time.
Your external corners, you will find that the steel thin coat beads much easier to fix, the too are more durable and want damaged when applying your coats.
The cost of a roll of flex corner tape and adhesive, compared to two lengths of thin coat bead?
And to say it is just a man room, if your missus is anything like mine your heading for a fall

with regards to the ceiling were you meaning that i insulate and batten the walls first and then put the ceiling plasterboard on before the wall plasterboard ?

still not sure on the plaster skim coat as i am on a budget here hence just taping and painting

its was the wifes ides lol

 

[PrenticeBoyofDerry]

with regards to the ceiling were you meaning that i insulate and batten the walls first and then put the ceiling plasterboard on before the wall plasterboard ?

Indeed I do.

still not sure on the plaster skim coat as i am on a budget here hence just taping and painting

You will find cost of joint taping, quite surprizing!

its was the wifes ides lol

I dream of the missus having ideas like that

 

[dotnetdave]

You will find cost of joint taping, quite surprizing!

I can find it on screwfix for £5 a roll

 

[PrenticeBoyofDerry]

I can find it on screwfix for £5 a roll

That's the rolls of tape, what about the joint compound to fill your joints out with(three applications per joint). ie easifill and the sandpaper that will be needed to sand/smooth the joints down.
It's not just a matter of throwing some tapes on then painting over it!
The joints need to be filled out.

 

[dotnetdave]

another couple of questions

1) Should the insulation boards and plasterboard for the walls sit directly ontop of the floor dpm or shoudl them be raise up by around 25mm

2) Where the ceiling and walls meet how should i seal the gap, with joint tape, caulking etc

 

[PrenticeBoyofDerry]

another couple of questions

1) Should the insulation boards and plasterboard for the walls sit directly ontop of the floor dpm or shoudl them be raise up by around 25mm

There should be no problem with the insulation boards sitting on to of the DPM, but I should lay your plywood floor before boarding out then leave a slight gap of about 25-40mm between floor and plasterboard.

2) Where the ceiling and walls meet how should i seal the gap, with joint tape, caulking etc

The right angle joints between ceiling and wall boards, should be taped.
May I ask a question?
Do you want some guidance on how best to joint tape?
(sorry that's two questions)
Presuming you still wish to go ahead with this method and I assume this is your maiden voyage.
One other thing when insulating walls and ceiling voids, electrical cables should not be totally surround by thermal insulation, this effects the power circuits more often than the lights depending on fuse ratings and cable sizes.
I can help you with that too!

 

[dotnetdave]

I had been advised to have the plasterboard go down below the floor level so that the cold spot of the wall is under the floor rather than at floor level.

the wiring will be going down the batten cavity between the plaster board and insulation

for the joints i am just going to use tap and jointing compound to smooth out and sand and fill the screw heads. After that a couple of licks of paint for the man room

 

[PrenticeBoyofDerry]

I had been advised to have the plasterboard go down below the floor level so that the cold spot of the wall is under the floor rather than at floor level.

Never seen that done, that could subject the plasterboard to moisture at the lower level, the plaster within the board could quite easily soak any moisture up and in to your room.
I would seal the insulation and DPM together but not drop the PBs below finished floor level.

the wiring will be going down the batten cavity between the plaster board and insulation

so non in the ceiling void then?

for the joints i am just going to use tap and jointing compound to smooth out and sand and fill the screw heads. After that a couple of licks of paint for the man room

Use the self adhesive nylon tape for your joints, this will prevent dry spot bubbling and blistering.
The tape should be layed flat to the surface, it is best to apply three applications of joint compound, waiting till dry after each application and a light sand after the first two application, taking away any snots, lumps and scratch lines.
Each application should overlap the previous one, until your joint is feathered out about 150mm of the joint.
On the drying of the third application, this must be sanded down to smooth, level and even, without breaking in to the tape or the board paper.
150-180 grit paper is best used.
a little trick is to use a damp cloth or sponge on the edges of the joint compound, whilst drying, smooths it off a little, makes the sanding a little easier.
The wall should then be primed by either a drywall sealer or mist coat.
Before you slap on your paint.
Don't forget your PPE, dust mask, safety goggle/specs a must have.

 

[dotnetdave]

its a pitched roof on the garage the cable all ready run up the trusses to go across to the other side so shoudl be no issues there

 

[dotnetdave]

I had been advised to have the plasterboard go down below the floor level so that the cold spot of the wall is under the floor rather than at floor level.

Never seen that done, that could subject the plasterboard to moisture at the lower level, the plaster within the board could quite easily soak any moisture up and in to your room.
I would seal the insulation and DPM together but not drop the PBs below finished floor level.

i did think about that but wasnt sure as becuase the PB would also sit on top of the DPM them any moisture is on other side of the DPM aka the wall\concreate side. Also if i was to put the PB on last after the ceiling and floor it will mean i need to cut ever piece of PB for lengh as its not 8ft between the floor and ceiling.