Using a brick garage as a workshop

Have built/converted two workshops, one from scratch, one already built, both 'prefab' concrete and corrugated roofs. In both, the floor was covered with a DPM, then 50mm polyurethane ally-backed foam, then 3/4 inch t&g chipboard flooring. Walls and ceiling also poly insulation topped with 1/2 inch plywood. Heating was a thermostat controlled Dimplex oil-filled heater and a medium sized dehumidifier. Both over-filled and over-loaded with medium weight machines (M7, D-W mill, Fobco drill etc.). No rust, and comfortable for 'working'. The second was destroyed in the N. Sea 'surge' and the replacement (double skinned block and brick, in progress) will be similarly constructed. Can recommend the method.

rgds

Bill

If the surface shattered I would think it has laid incorrectly either dust or something else under it not allowing the compound to adhere correctly.

Bricks are porous some more than others as are the mortar joints so moisture will find its way through, even render is not a guarantee as render is porous. The trick is not to allow the moisture through to the inside face hence the use of a breathable membranes.

On our bungalow the gable end takes most of the prevailing weather and we found we had problems with damp on the inside, this was traced to a badly fitted lintel trays. When the property was built in the mid 60's they used lead as a cavity tray and over time it sagged forming a gutter not helped by blown in cavity wall insulation (hate the stuff should be banned) this allowed the water to run off the tray and soak the insulation and inner wall. All we did was tile the gable end above the windows problem solved.

Bob

I haven't had a chance to do to much more investigation, other than checking that all is dry in the rain yesterday, and it is.

Regarding the floor, it is almost up to the wall DPC, about 1/2"-1/4" lower, that and considering the garage was is from the 1960s I guess the is no DPM then. If I don't fit one, but make sure the internal walls/insulation are not directly on the floor would there be much of a damp issue? How much really comes up through the floor? Taking up the current floor and laying a new one may be the ideal answer, but rather time consuming and expensive. If I paint one of the DPM pains on the floor/lower wall before adding the self levelling compound will that provide adequate protection?

Looking at the walls, I was planning on putting the electrics in surface trunking to allow for easy changes, exactly as suggested by Bob Unitt. I had thought of using ply as the finish, but seeing the price of OSB compared to this I might use OSB, looking around it seems to be OK, has anyone anything to say this is not the case?

Baldric

Do you need a DPM if using a damp-proof screed?

Some many years ago I decided to rip up old cork tiles in the utility room of that house. After spending an hour failing to get one off the floor i lost my temper and decided to bury the lot under a 3" screed and retile with ceramics - there was a step down into the room anyway.

OH (typically) demanded the whole job complete within 3 days. Further investigation found bare earth under a section of lino at one end of the room. I dug that down 6 inches, layed wall battens to screed from.. hand mixed some 30 wheelbarrows of concrete with x/s waterproof additive and covered the lot. 2 days later I started tiling - got told off for it taking nearly 5 days to finish the whole job (shesh!) but there was never a damp issue

You could just level any big depressions, put down a large sheet of heavy duty polythene that runs slightly up the walls, taping any joints with duck tape. Now lie a simple floor of 18mm ply,or OSB on top.

I have had no problems with OSB, as it is intended for load bearing use, but the heaviest tool I have is an X2 mill, not a bridgeport...

bct.eco.umass.edu/publications/by-title/choosing-between-oriented-strandboard-and-plywood/

"OSB is our future"

Neil

Hi Baldric

If you do use self levelling compound You will need to check the floor for level prior to using it. It can work out quite expensive if you have large depressions to fill. I would check level the floor first by placing stacks of thin MDF squares of varying thickness, or whatever other sheet material you have to hand in a grid pattern using a builders spirit level on top of any two stacks then cross checking adjoin stacks and adjusting them. Try to start at the highest point. With a good level you should be able to establish a flat plane within a few mm. If you have access to a good quality Laser level you could use that to level the stacks. You will then be able to calculate the quantity of material required. The alternative is to drill the old floor and using a cheap plastic plug set nails or screws in position levelling them as you go. (make sure the hole is deep enough to allow the nail or screw to be hammered in later) when the new floor is being poured they can be left in position until the pour is finished. They can be driven in with a hammer and the finish touched up with a trowel as they are no longer needed. This is the way truly professional concreters (if you can find one!) work. If on the ground they use short wooden pegs.

When you set the nails or screws watch out, they are a nasty tripping hazard.

If the floor is dirty or greasy it will have to be cleaned first. Once cleaned There are materials available to assist bonding In Australia one well known brand is called "Bondcrete". This should reduce the chance of the new coating delaminating from the old floor.

levelling compounds are not very strong. They are usually covered with tiles or other flooring.

Oh and pre fill every hole and crack, the ends of formwork are a favourite spot, anywhere the levelling material can get away. If you don't it will disappear, in the end leaving a depression in the finished work..

If the floor is cracked the floor will crack again at the same places as the existing cracks when the floor moves, and it (will) move again. If it is badly cracked It may be better to replace it if it is for long term use.

Regards
John

Edited By John McNamara on 20/05/2015 15:55:11

John,

Re the strength of the levelling compound, the one I linked to says it is suitable as a finished surface, under the FAQs it says OK for a garage so I assumed this is a stronger one, I did also find floor repair compounds for factory use that can have a feather edge so I guess they are good, but perhaps not self levelling. The hints about using screws to mark out floor levels is a very handy hint.

pgk pgk,

I will look for a thin floor screed with waterproof additive so I don't loose the headroom and compare with a "paint" and screed.

Baldric

I helped a friend insulate a concrete panel pitched roof garage as a workshop.

We merely patched the floor, to get it somewhere near level, before covering it with chipboard.

We insulated the walls with polystyrene sheets and covered that with a polythene sheet as a vapour barrier (DPC) (taking care to position the wiring where it would be safe from screws or nails), before fixing 6mm ply panels as the inner wall. The steel roof trusses got much the same treatment, except for the DPC and plywood panels.

So far, there seem to have been no problems with damp or rust, on the lathe, or materails. (He uses the one end to store some of his two wheeled machinery , none of them show any signs of distress several years on)

Howard