New workshop, advice required!

Hi guys, I have just moved into a new house which has a large double garage which I am going to use as a workshop. The space is great but unfortunately it needs way more work than I realized. (Thanks ivy)🙄 The garage is a single skin of red brick with a concrete tiled apex roof.

Before I fill it with tools and machinery I would like to redo the roof. I also want to insulate the ceiling and walls. The floor might need leveling too. I am not a builder so I have many questions, which I am hoping you guys can answer along the way! 😉

First questions -

which membrane/sarking would be best to use under the tiles?

How difficult is it to fit a velux type window?

Would 50mm of insulation with a 1 inch air gap be enough to keep the chill off?

Edited By Hollowpoint on 27/09/2023 08:38:19

Edited By Hollowpoint on 27/09/2023 09:01:18

Workshop insulation has been covered numerous times in the past, so a search may answer you questions, and possibly give you some pointers you hadn't eventhought of yet.

Posts like this Roof insulation

Thanks. I have read though lots of old posts and I have a general idea how to tackle most of the work. I still have many questions specific to me though.

If it is watertight you might consider having an initial arrangement of an inner room say 8x6 with a ceiling with 6in of insulation and walls of 4in that you can keep background heated and dehumidified to keep al the important stuff in.

I’ve had two garage workshops and have to say working on a bare concrete floor is dreadful. I tried mats etc but they just trap swarf etc. I currently have a shed with an insulated floor and floor boards covered in plywood with floor paint. If I had to use a garage again I’d definitely cover the floor with boards or something.

Fitting a velux light may be easy - making it watertight could take more work. Noel

If the roof is tiled, and weatherproof, my advice would be "Don't disturb it" You might cause a problem that wasn't bthere before.

DEFINITELY insulate. If possible, rather than disturb the roof, as already suggested build internal partition walls and false ceiling, insulated with at least 50 mm of glass fibre..

But do build in a little ventilation; a small fixed vent near to the floor, and another close to the ceiling

Concrete floor will be hard on the feet, so lay a false floor above it, preferably insulated, to keep your feet warm.

Hesating should be "dry", ie electrical, not combustion of any sort.

HTH

Howard

Totally agree about working on bare concrete floor. I covered mine with interlocking rubber matting. Had to cut it to go around machines but works great and quite cheap. It's also not as cold. Regarding heating, I use a small electric oil heater controlled by a thermostat. I switch it on at the end of October and switch it off in March. Never heat with a naked flame source as it will generate condensation.

Alan.

I have the interlocking tiles on the garage floor and simple waterproof chipboard tongue and groove jointed underflooring sheets in the workshop. Both on concrete.

Both are effective and both vastly better than bare concrete. Tongue and groove probably a bit cheaper but, despite being nominally waterproof, best not to use where things could get damp. Like a garage if you keep the standard door. Interlocking tiles prettier.

If you stay with a standard type door pay attention to sealing round the sides and bottom. The interlocking tiles have edging ramps which can help fill gaps. Alternatively the triangular glue down rubber strips about 1 inch high by 4 inches wide are very good. Cut it half in you don't want a dip on the backside before getting to the flooring. Cable cover strips are effectively same thing but much easier to cut due to cable hole rather than solid rubber down the middle.

Clive

I have fitted two Fakro brand Velux-type roof windows without problems. Both required removing a section of rafter and "trimming" round the aperture.

The (Polish) Fakros came with good instructions.

I believe Velux claim that their windows can be fitted entirely from within the roof but you might have to attend their academy first!

yes velux windows can be fitted from inside but you will need to go on the roof to get the tiles off

Thanks for the advice so far everyone. The roof has been heavily damaged by ivy and I feel it is well beyond simple repairs. My plan is to remove the tiles, re-felt and fit a dry verge. The pictures below show the condition.

There's no harm in Ivy - ALLEDGEDLY

One thing I would consider is splitting it into 2 with a partition to provide a small store room. Depends a little on the shape. My workshop started out as a bigger than double garage but smaller than a treble but with an up and over door on the short side. My store separates the short end door from the main space. The main advantage is you generate more wall space for cupboards shelves and racks etc and with the partition you get to use both sides.
Put in way more sockets than you think you need, I figured out what I required and then doubled it. I have a split consumer unit with lighting on an RCBO separate to the power distribution and protection so that if something trips the lights stay on. I have 2 ring mains which again provides flexibility like being able to shut one down to work on it and still having power to hand. My floor is self levelling screed with insulating underlay beneath flooring grade chipboard which is painted. I have single skin brick walls which have been battened and then a sandwich of 70mm celotex and floor to ceiling 12mm MDF. The beauty of that is if you wish to fix anything to the walls you can screw straight to it. The cables run in the space between the celotex and the brickwork crated by the depth of the battens so povided the screws are less than 80 mm there is no possibility of hitting a cable. The ceiling is fibre board with rock wool insulation and then boarded in the loft space which again generates a huge amount of storage.

The lathe sits on steel bushes extending through the flooring and bolted into the concrete base, everything else just sits on the floor.

regards Martin

A note of caution with respect to the single skin brick wall. Many years ago I had a similar construction and found that water penetration, especially with driving rain, was extraordinary, i.e. water running down the inside of the walls. The type of clay brick used was an issue but the problem will occur to some extent with any single leaf masonry wall. Use of a clear sealant on the external surfaces helped to a great extent but was not perfect.

In your situation, in addition to sealing the external surface, I would suggest a waterproof membrane on the inside. This could be a brush on type or sheet foil followed by battens and an inner skin comprised of ply, particle board or similar - moisture proof for preference.

I have no issues with concrete floors re comfort ( where there is no sense there is no feeling ) but depending on construction ( i.e. use of a sub-floor damp proof membrane ) this can also be a source of water ingress. A coat of paving paint or use of an epoxy coating may be required.

A reflective membrane under the tiles and as much insulation as you can fit in would be highly recommended. Something lacking in my current workshop, which is double brick and has fully addressed the moisture problem associated with brick walls, which gets very hot in summer ( Australia ) and surprisingly cold in winter.

You will need to assess your own situation and local conditions in assessing which actions will give the greatest benefit.

Good luck

Pero

Replace the sarking felt where it is damaged and then use 4" of rock wool insulation (use the one with paper attached) underneath that. Hold it in place with light wooden laths running the length of the roof.

Batten a waterproof membrane to the exterior wall and then use insulated plasterboard.

Up and over door needs lots of insulation, draft stopping would be advantageous.

Ceiling - make it fireproof with 2 layers of plasterboard ?? but with good access for storage, but if you wanted Velux lights, scrub that idea.

All the above, check out with a builder who knows what makes sense.

Bob

My workshop was originally built at one end of a sectional concrete garage with shallow pitched roof. The concrete floor was screeded to avoid any water ingress at that level (the vertical wall sections were sealed only on the inside sections, so driving rain, that might access the small gaps on the outside would go out, not under and in). I didn’t add any extra insulation at that time, but would do now, if I were to start again!

150mm+ of rock-wool insulation was added and supported by old garage doors (cheap as chips), as the internal construction - both as walls and ceiling. The ceiling was covered with 150mm of rock-wool.

That sufficed until I twice extended my workshop area. I extended with insulation sheets. The walls are 100mm Celotex/Recticel (1200x2400mm). At the same time I added 25mm of Recticel to the garage door section - wish I had fitted more, but space was limited).

I sourced the equivalent of about 7 1/2 full sheets of 100mm PU insulation from a regular dispersal sale (near Kidderminster) in mostly 1200x1200mm and 1200x600mm sizes. The 100mm celotex/recticel sheets were purchased at an auction site I regularly attended. The cost of that insulation was very cost effective

The internal surfaces have been covered with variously-sourced ply sheeting. I don’t weld or plasma cut inside my workshop. No windows and a fully insulated door maintains a warm environment in winter and a cool one in summer. I am adding more insulation over the workshop as and when I can. My internal construction fell nicely just under the roof supports, with an eaves height of 8’ 6”.

For yours, I would repair the roof problems but leave the rest as is. The pitched roof, with non-asbestos corrugated sheets, is no longer available as storage for mine. Fire safety measures are likely higher for your installation, so mine might be not appropriate for yours. Thicker layers of rock-wool are likely a better choice.

Ventilation is required if dry-cutting with cutting fluid - not a difficult addition. Good luck with your installation. Mine was done on a tight budget, over a longish period of time.

It looks like you have, or had, a roller shutter door. My workshop is a pre-cast concrete garage and I replaced the door aperture with a 'site office' type front with 4ft double doors and the largest window that could be fitted. The outer skin of the front is boarded in ship-lap which is protected with Sadolin. Your garage may benefit from a similar arrangement rather than retaining a roller or up-and-over door. Although I have the large front window and four smaller windows down the side of the building they are mostly obscured by shelving to the point where it is always necessary to switch the internal lights on, whatever the time of day, so you may not need a Velux window in the side wall which will diminish the overall security of your workshop overall. I think we must all live in fear of a break-in and losing irreplaceable tools and models. I have a workshop burglar alarm fitted, security lights all around the house and lately four CCTV cameras recording 24/7 but it didn't stop the b*******ds relieving me of my then new big-screen television and restored antique time recorder in broad daylight whilst I was out at work.

Workshop front built into up-and-over door aperture.

Further to what Peo says single skin walls or ordinary brick and not waterproof in the UK.

Ever.

Whatever nostrum is applied to the inside.

There is a reason why relatively modern UK construction has been based around cavity walls. The thermodynamic and humidity variation effects of a cavity are far more complex than many "experts" would wish you to believe but they allow you to use a relatively porous "common stock" brick for most of an exterior wall.

You pretty much have to put some sort of gap in between brick wall and the inside face to be sure all will stay dry. Impervious insulation fill is generally OK. Fibreglass probably theoretically little better but any difference is unlikely to matter unless the wall in question faces high winds and driving rain.

I found OSB sheets with several coats of white emulsion to be an aesthetically satisfactory internal wall and easy to do.

Often forgotten that the UK has one off the most brutal climates when it comes to building survival due to the repetitive cycling of atmospheric and building surface temperatures through the dew point of a generally damp atmosphere. Not forgetting getting pretty hot on a fairly regular basis. Most other regions get either hot or cold and stay there for months on end.

Clive