Some advice required please: I am attempting to convert my single car, single skin garage into somewhat of a bike/man cave, workshop and bikes at the back and a spot for some gym equipment at the front.

I started a few weekends ago removing all the old cupboards and shelving units and gave the garage walls and floor and good sweep so I could paint the inside walls with Masonary paint this weekend, there were a ton of cobwebs when sweeping up but I had assumed these had amassed over time. However when going back this weekend, a lot of them are back! I have noticed that the bricks and mortar dont touch the roofboards in quite a few spots, and on the outside there are facia boards but they have a gap behind them letting nature come and go as it pleases.

What am I best to use to seal this gap to slow down the ingress of the outside world? Could I get away with just some silicon sealant in the gaps? or would I need to use mortar? I am assuming this gap isnt for air flow and there would be no issues to filling it? There are still gaps around the up and over door which would let air circulate when the door isnt open.

Seal it up and the place will be dripping with condensation before you know it, especially if you use it a gym. Insulate the walls, and roof, breather membrane etc and get a usable space.

Seal it up and the place will be dripping with condensation

Ah bugger, dont really want this to occur, I would have hoped the roof boards would have allowed hot air to be released, this with the gaps around the up and over door would have given it a good airflow. Chatting to somone in the office, they have advised using expanding foam to fill the gaps.

Is it attached to the house? If not – it will be quite hard (i.e. expensive) to make it into a truly useable mancave.

If it is, it will still be expensive to do it properly, but you’ve got a better chance of making it work and it might add some decent value to the house, if that sort of thing is a concern…

Why would it be any harder if it was attached to the house? Other than an armoured cable required to power it as opposed to a normal cable out the board i can’t see any difference.
As for condensation it will be an issue. Even a 50mm batten on the inside with a 25mm cellotex or similar board in the gaps will help massively. You could then just tongue and groove it or do as I did in my big summerhouse/shed and use osb ply the inside. All adds up though.

Is it attached to the house? If not – it will be quite hard (i.e. expensive) to make it into a truly useable mancave.

No, its detached. It does have power to it already. There is a light and two power sockets.

The condensation issue I might have, is this rising from planning to use the front portion as a gym? or would my plans to fill gaps, paint the walls and re paint the floor cause this? I’m more keen for a workshop and bike storage use than the gym usage. I can always keep the gym stuff in the house and annoy the wife…

Single skin is cold, literally to the touch, you will, even through respiration create warm moist air, if you are doing a bit of tinkering with bikes you may want to put a heater on to take the chill off, all these things will cause warm air to hit the “cold” surface of the brick, thus creating condensation on the inner face. All depends how usable you want the space.

You’ll get condensation because the walls and roof will be icy cold so any moisture you generate, from breathing for example will just condense to water. My garden shed suffers, especially on the outside of bottles of liquid, like brake fluid or spray cans etc, not so much on the shed itself.

Why would it be any harder if it was attached to the house? Other than an armoured cable required to power it as opposed to a normal cable out the board i can’t see any difference.
As for condensation it will be an issue. Even a 50mm batten on the inside with a 25mm cellotex or similar board in the gaps will help massively. You could then just tongue and groove it or do as I did in my big summerhouse/shed and use osb ply the inside. All adds up though.

I know you’re a builder so I defer to your expertise! But I said it would be harder if it wasn’t attached to the house, because: (i) you’ve got at least one less insulated wall in play already; and (ii) having to go outside to access your gym / man cave is a bit of a pain – it would add more value if you were effectively adding an extra room to the house. Not that that is the most important thing of course, but I find it easier to spend money on the house if I’ve got a decent chance of recouping it at some point, should I need to.

(ii) having to go outside to access your gym / man cave is a bit of a pain – it would add more value if you were effectively adding an extra room to the house.

Our workshop is 50m away at the end of the garden, not as convenient as being next to the house, but it’s really not a big deal even when raining.

I floodlit the garden path to it to make access easier at night..

[url=https://flic.kr/p/pWyUPo]12v 10W LED flood lights[/url] by Ben Freeman, on Flickr

reading with interest. i have a detached single car (new build) garage which has my very modest gym equipment and bike stuff/workbench in it. Don’t have the funds to deck it out with creature comforts, but training for me in the winter is more enjoyable when its actually below zero inside the garage. Makes me work harder, and I’ve managed to train shirtless as low as minus 5 inside. Its never been an issue with the temperature. I’m a bit weird though. The animal carcasses/punch bag whiff a bit when warm.

How porous is the brickwork? My garage leaked like a sieve when windy and raining. I lined the inside with thick polythene sheet, 50mm battons with insulation between and 12mm ply on top. Now dry, only condensation issues are when I use the gas heater for extended periods.

I have a single skin detached garage. I only get condensation on the garage door after an hour on the turbo. Soon dries out. Mainly use mine as bike storage, turbo station and general DIY storage – never have an issue with damp. I do have a small tube heater on just to ensure the air doesn’t get too damp, and there is plenty of air circulation.

I’ll only occasionally need a fan heater on, if it’s sub zero outside, when maintaining the bikes. Being cool is better for turbo training, and I still use two fans to keep cool.

I’ve done this with a couple of single skin garages. Screw some of that cheap 2 by 3 batton from b&q to the walls, roof insulation then either plasterboard or chipboard – which is great for hanging tools on. Fill any gaps with ready mix, over foam if a big gap. Wallpaper lining and paint.

For the ceiling Wickes have some really cheap cladding. Simple to put up.

At one point I split with a studwall built the same way. Never had any condensation issues but a bathroom fan over mesh would solve it?

Our workshop is single skin brick. I lined it with Cellotex and sealed all the gaps with tape, so it’s pretty much hermetically sealed now. No problems with condensation or damp in there. Heat it with electric fan heaters and vent it with windows..

How porous is the brickwork?

I’d say not very, when raining or windy the only areas where damp sometimes appear are around the garage door corners. The garage door has a 5-10mm gap underneath it, I plan to get one of those rubber strips you can attach to the base of the door to stop water ingress here.

This morning after reading the above posts I looked over on Pistonheads and most posts are split as per the replies here, people have either insultated and fitted out or left it or painted it and its been okay. I think for me I am going to expanding foam the gaps where nature gets in, brush it well and slap on a coat or two of masonary paint on the inside walls and will repaint the floor too and see how it lasts. If either start to flake then Ill have to look at insulating it when I have some money!

Insulation back plasterboard walls and plasterboard with thicker roll insulation in the roof in my attached garage.

Usable all year round and a damn sigh better than how it used to be

My garage is cold, unheated but vented aplenty, gaps around the door etc.

The upside is I can leave my bikes and motorbike in there completely soaked and they dry just fine. I also hang up tarps/tents in there to dry.

I have a workshop in there as well. In the depth of winter it really is cold in there but most of the year it’s fine. It’s definitely warmer than the outside, as it’s attached to the house, but there’s no condensation in there

Leave it drafty. Keeps the condensation down. Just out a coat on, electric blanket if you are too cold sat down.