Workshop Flooring Selections

[shu]

Hi guys, Happy New Year!

Hopefully I'm in the right place to ask this.

I'm building a workshop in my garage and get stuck in flooring selection.

1. Water proofing
As the garage is semibasement, ie. the back and sides are half underground, and the front is above ground on a slopping site, I'm planning to put a subfloor with raised drain to allow raised moisture or condensation water to pass. I only find a local product called Platon Stop but yet to check if it will work. Any suggestions for Melbourne area?

2. Level the floor or follow the fall
The existing garage concrete floor has a fall of approx. 100mm from inside to the door. Should I level it or just follow the fall? The garage door opening is 2.4m in height so height is not an issue if it's leveled, ie. raised at the garage door.

3. Laminates or solid timber
Laminate flooring is cheap, easy to clean. But will it be too slippery with dust on it?
If I can find some cheap pine floor boards, that would be ideal. But will it worn soon and require lots of maintenance?

Any other options that provide a balance of 'timber feel' and easy-to-maintain for the purpose of a wood work / clay make shop?

Many thanks.

[Beardy]

If there is a dampness/ water issue with the floor you are asking for trouble laying a timber floor over it.
The likes of Platon Stop are not designed to deal with a waterproofing issue but designed to allow any residual moisture in a curing slab to dissipate

[shu]

There is no obvious water issue in the past 15 years however this is a semi basement, who knows if we'd get a broken pipe from the neigbour net year.
Is there any alternative that perform as a proper subfloor underlay in Melbourne?

[Chris Parks]

I have the exact same problems as you describe and put a floor in as you describe. First step before doing anything is waterproof and stop all leakage as one the water gets under the floor it is slow to evaporate and we had to install solar fans to encourage more air exchange in the room. Luckily we did not install the floor hard up to the walls and even after we had water proofed the internal wall and the join where the walls sit on the slab it was still necessary to go back and do some remedial work to stop the leaks altogether. My situation was the the walls had been built on the slab where they should have been built on footings and the slab poured inside the walls so water ran down the outside, settled on the slab outside the walls and seeped between the wall and the slab.

I used hardwood floor joists bolted to the slab and screw yellow tongue flooring to that and carpet was laid on the yellow tongue and we have had zero problems in over 20 years. lay the floor level, it is the sub floor that needs to have the fall on it. After waterproofing I would be patient and wait until it does not leak in heavy rain. We thought that it would not leak and heavy rain proved us wrong. Prevent the moisture getting in as allowing it under the floor will not make a pleasant place to work. It sounds like the walls and floor are not built yet, if so make sure the walls are installed first then the slab poured.

[Beardy]

There is no obvious water issue in the past 15 years however this is a semi basement, who knows if we'd get a broken pipe from the neigbour net year.
Is there any alternative that perform as a proper subfloor underlay in Melbourne?

That is good, you can apply a waterproof membrane over the area that will withstand hydrostatic pressure as a safeguard before laying the floor. There may well not be a plastic underlay under the slab if it wasn’t going to be used as a habitable area.
If you are getting a bit of decent rain you can do a test by laying a sheet of plastic over the slab and see if you get any condensation appearing. It is a basic test but will give you an idea.
You don’t want to go to the effort and expense of installing a new timber floor only for it to suffer moisture damage

[shu]

Thanks Chris and Beardy. That’s really helpful.


In regards water proofing. I believe it needs to done from outside, when the house was built. IE., proper tanking, membrane under the slab, aggi pipe, etc. But I doubt these would still work for it’s an 50+ years old house, if they had actually been done. Even if the test result was positive, I don’t want to take the risk.


So my thinking is:

• Build a subfloor with raised drain to allow water to go along the fall of existing slab.
• build stud wall on top of the subfloor, and leave a gap from the existing masonry wall. Of course the stud wall is water proofed with wrapping

In this way, a continuous gap is created. Any water coming in can go from the existing wall to the floor, and all the way to the lowest point at the garage door.


What I’m not sure is whether I need to install some fan to force ventilation, as there would hardly any natural ventilation in this gap.


Any comments on this system?


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@chris I will level the floor as suggested


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Any comments on timber as flooring of a workshop?

[yvan]

Shu,

Is it too difficult to prevent this water from entering into the building in the first place?

Cheers
Yvan

[shu]

Yvan,

There has been no obvious water entering for the past 15 years. I can see some raised damp but that's it. All water proofing preparation is for extreme possible situation only. A bit overkill?

Thanks

[lyricnz]

With no sign of actual water ingress, I'd just lay some H3 pine bolted to the slab, with 5mm packers underneath to create a gap and a way for any water to flow, then screw yellow tongue to the top.

Macsim Fasteners 5.0 x 75mm Window Packer - 200 Pack | Bunnings Warehouse

[shu]

That makes sense to me Lyric. Thank you. I may just calculate the additional cost against the head hight saved if using PVC premade subfloor. Not essential though for the PVC's 20mm vs the pine's 66+5=71mm.

Besides the 5mm gap underneath, I also need to level the floor. The existing slab has a fall of 100mm. How would you do it?

With no sign of actual water ingress, I'd just lay some H3 pine bolted to the slab, with 5mm packers underneath to create a gap and a way for any water to flow, then screw yellow tongue to the top.

Macsim Fasteners 5.0 x 75mm Window Packer - 200 Pack | Bunnings Warehouse

[lyricnz]

You do want a bit of a fall in the slab to help with water egress if it happens (so that's good), but 100mm is probably more than you want in a shop floor (presumably that's over about 6m, if this is a garage).

The flooring screws directly to the joists, so if you want a level floor, you need to pack/raise the joists more as you travel down the slope. I think 100mm is too much for just spacers, so maybe you want to use thicker timber for joists at the front, or just pack 'em up with some timber beneath them. A laser level will help here, if you can borrow one.

I would normally prefer to have the flooring running front-to back (which means joists left-to-right). Easier to install, and any front-to-back levelling issue is along the length of the yellowtongue, not across its edges.

Disclaimer: I'm not a builder, or have any expertise at all!

[RossM]

Why do you want to lay a timber floor?

If the concrete is sound, why not seal it? If it's uneven, you can level any significant dips. You could seal using an epoxy or acrylic finish. Or a terrazzo or sand/epoxy coating.

If the timber is for aesthetic reasons, fine, go for it. If it's because of a notion that timber is easier on the feet, just invest in good quality footwear - way cheaper.

[Beardy]

What Ross said or if you do want a timber floor start with a 19mm thick battern at the highest part of the floor and then use thicker batterns as the fall permits you to use. 70 x 35 or 45 on flat and then on edge as the height permits. Either use plastic horseshoe packers and or solid timber blocks to pack level and then skin with sheet flooring. You could look at using sheet ply and have that as a finished floor with an appropriate coating

Before you start the battern process cover the entire floor with builders concrete underlay plastic as a moisture safeguard

[reccymech]

Any comments on timber as flooring of a workshop?

A few years ago, and I do mean a few, I was at the RAAF Base Wagga Wagga and at the engine hangar the complete flooring system was wooden. It was kept at an immaculate polished standard. I happen to ask as to the 'why' of the hangar floor being wooden. Reply was that if any parts were dropped it would not damage the part, as opposed to a concrete floor.

Sounds about right. Anyway, for what it's worth that may or may not be of interest.

Cheers.