Garden office plans, any advice?

[Deluks]

Conduit trunking - plastic pipe or channel that clips to the wall to run the cables in between sockets, and the sockets themselves sit proud of the wall. Save making loads of holes in your vapour barrier like you would with flush sockets.

Thus you only break the insulation once, when the main incoming cable enters the room. Also makes running the cables a piece of ****.

Downlighters would be ok, but you create holes in your insulation, fiddly to fit, crap lighting of the room, transformers fail etc (can you tell I'm not a fan!)

Better to fit a spotlight bar. One cable feeding 4 lights, directionable to suit your needs, easier to change bulbs etc

 

[Timmophoto]

That sounds alot easier with the cables and sockets, good thinking.

My only main reason for downlighters was head space, as the height is only going to be 2m or so. I will look into other lights, maybe something wall mounted would suit better anyway.

Is there any grades of vapour barrier? I am looking at the moment and it looks like its just the one option at most places, is this screwfix one suitable for using on the walls and ceiling?

http://www.screwfix.com/p/vapour-barrier-2-5m-x-20m/12869?_requestid=414070

Also is there a particular method for joining/overlapping the two, i.e ceiling v. barrier first all the way to concrete wall and then build the wall stud and v. barrier that after?

 

[Deluks]

You cover all wall and ceiling areas internally with the vapour barrier, it's the last job before the plasterboard goes on. The SF stuff is correct, buy some pvc tape to go with that, and tape all joints, wall and ceiling should be continuous.

As mentioned, foil backed plasterboard is easier but more expensive.

 

[flameport]

My only main reason for downlighters was head space

Forget about downlighters. The ceiling would need to be at least 150mm thick to accommodate them. Even if it was, every downlight hole will be a location for air to enter the ceiling void, where it will cause condensation and mould.

As already suggested, 50mm of wall insulation is far too thin, 100mm would be a realistic minimum.

 

[Timmophoto]

Even if I could manage to put more insulation in the Walls it would require a lot more funds if using kingspan. Is there an alternative of dong the same as the roof, polystyrene against wall then fibre wool infront?

I was under the impression that the roof would be more important for optimum insulation. I cannot really afford to loose much more of the room size so feel that compromising at 50mm on the Walls may be necessary. After all it is a ditached garden office rather than a new sitting room in an adjoined garage.

Point noted about down lighters, I will look at alternatives when I get a little closer. As for today I thinks it's time to empty the garage, this could be the hardest challenge if them all!

 

[Deluks]

For a garden room I wouldn't be spending on expensive stuff unless I could get secondhand/offcuts/seconds. Polystyrene sheets and loft roll. I would try and get min 50mm in the floor, 75mm in the walls and 150 - 200mm in the roofspace.

You can get insulated plasterboard too, expensive kingspan stuff as well as a cheaper polystyrene backed one.

 

[Timmophoto]

Floor down. Ended up with a good deal on 50mm kingspan. Tomorrows job is to start on the stud work. Going to use fibre wool for the Walls and ceiling, couple of quick questions though.

If using just fibre wool, can it be touching the concrete walls? If not, should I line the wall first with 25mm polystyrene?

Once insulation is all in, I cover with vapour barrier before plasterboard. However how is this secured to the stud? Is it ok to staple it?

 

[Timmophoto]

Here are my two options as I have gathered from all of your advice. Obviously these are both methods avoiding the use of kingspan. Apologies for the rather crude sketches in photoshop, hopefully they describe the options though. Any thoughts would be appreciated.

[/img]

 

[Deluks]

2nd ones alright, only one insulation type needed, less hassle. You would be wise to cover the outside (before the battens go on) with a cheapish roof breather membrane. This gives a continuous weatherproof layer underneath the cladding, and will ensure that the inside remains dry yet ventilated.

Staples good for the vapour barrier, I also use double sided tape to hold it in place temporarily.