Garage conversion, how to prevent potential water damage

[untrepid]

Hi,

I'm gagging to try to split my long garage into a workshop and a rear "den" type room. it's built out of 1.5m X 0.5m stacked concrete slabs which are clamped to vertical posts ever 1.5m. So in my mind I should be able to bolt timbers to the insides of these posts by replacing the existing bolts with longer ones and knock up stud walls and internal wall surface from then on.

My query is about what I need to really look to do to ensure this doesn't all turn to sh*t with issues like damp and such. The inside is generally very dry, but is "aggresively" ventilated due to a corrugated roof resting above the smooth wall surface (previous owners appear to have blocked some of the holes with bits of soft foam), and some furniture and paper that have been in there over the winter have started going mouldy. Need to do something!

As I'm hoping to insulate a bit with fibre glass insulation and the likes, I assume I'd be stupid to not do something better before I start on the fun stuff, but I'm not really sure what. Do I just need to deal with the holes (currently waiting for the temperature to rise a little before using some expanding foam in a can), or should I line the walls themselves with plastic sheeting or something?

Suggestions appreciated.

Thanks

Chris

 

[RedHerring]

My post is not going to be very helpful but:

A long time ago I was out in the sticks looking for a small place and I couldn't find it. So I stopped to ask directions from am old fella'. He looked like he was from around those parts.
I said "Excuse me, do you know how I can get to xxxxx?"

He said, "well now lad, if I was going to go there I wouldn't start form here."

Sorry to be so negative.
Perhaps one of the more knowledgable posters will cheer you up.

 

[untrepid]

My post is not going to be very helpful but:

A long time ago I was out in the sticks looking for a small place and I couldn't find it. So I stopped to ask directions from am old fella'. He looked like he was from around those parts.
I said "Excuse me, do you know how I can get to xxxxx?"

He said, "well now lad, if I was going to go there I wouldn't start form here."

Sorry to be so negative.
Perhaps one of the more knowledgable posters will cheer you up.

You're right, that's really not useful. Indeed, not worth posting at all. Thanks.

 

[mointainwalker]

But are you really, really saying you have concrete slabs 0.5 m ( that's 18 " thick )

If so how much does pour garage weigh ?

 

[RedHerring]

Sorry, feel guilty now
If you post some pics, maybe someone can give you some useful advice. My personal opinion, fwiw, is that it's going to cost more money than it's worth, 'cos of where you're starting from.

I suspect, from what I've read so far, is that it's going to be difficult to keep the damp out of the walls and the floor. So I would say pics needed of: wall construction, including corners and joints with floor/roof.,
floor inside and outside where it meets walls, with details of construction if poss.,
roof from inside and outside with details of material if poss.

 

[RedHerring]

But are you really, really saying you have concrete slabs 0.5 m ( that's 18 " thick )

If so how much does pour garage weigh ?

No, No, No as Jim says (in Vicar of what'sit)

1.5 m long X .5 high, probably only 25-50mm thick.
I might have upset him but I could tell that. It's one of those concrete segment garages. I think

Sorry, should have said 1,5m long X ,5 m high for your part of the world

 

[noseall]

Concrete sectional garages are not the best structures to be converting. You would be better off building something else from scratch, or build a raised 'cell' within the garage, or indeed surrounding the garage with a better structure.

Silk purse - sows' ear.

 

[untrepid]

I'm certainly aware of potential issues, but I'm fairly sure that the structure is really pretty good outside of the way the roof joins to the rest, no sign of any water coming in from anywhere else etc, so I still feel it should be OK. Building a structure should be fine, very confident of that, just a case of the possible damp issues, including those I don't understand at all, if there are any. I think the raise cell concept is largely where i'd head, just maybe not so drastically.

Due to being dull, there's actually a video on youtube already if anyone is willing to have a look. Not great but a start... http://www.youtube.com/watch?v=L6Zkmcj1sHw#t=1m30s

 

[Deluks]

Cheapest way?
Build an inner single course wall of bricks almost touching the inner walls. Lay damp proof membrane over existing floor and these bricks, then build your stud walls off of this. 3x2 studwork will suffice.
Lay polystyrene floor insulation and t&g chipboard flooring onto dpm, insulate between studwork and apply plasterboard or plywood.

You'll then need to somehow make a false ceiling. Could attach timbers to the steel roof struts and hang PB from this, not forgetting to insulate above first (cheapie loft roll over garden netting)

These garages came with sponge filler pieces to reduce draughts between top of walls and roof corrugations, these often fall out and get lost. Best leaving the gaps there if you are going to proceed as above.

You will still need to vent the room, but vent thru to the outside, not into the cavity.

ps. Use foil backed plasterboard, or polythene first if using plywood. Stapled to the studwork and all joints tape-sealed.

 

[foz11]

Intrepid did you get anywhere with this project?

 

[Deluks]

Reading from the start I was just about to add my input, then I got to my own message from a year ago.