Thread: Pre-Shed Build Questions

Originally Posted by Pat

Christos, get the slab at 125mm, then cover it with yellow tongue flooring, your back will appreciate it, especially in the colder months.

Do you find the yellow tongue flooring slippery with a bit of saw dust on it Pat, or have you put a textured sealant on it? Do you happen to have pics of it on here?

I am very curious as I have been looking at getting my shed floor epoxied but the $$$$ have made me hold off. That and I am not sure it's the best solution. Putting down YT flooring is something I never considered but sounds like it has merit.

I too would do a slab + yellow tongue. The floor in my shed is done in the first generation yellow tongue on steel beams and it is over 30 years old. it used to be a garage but converted to my work shop so has had a variety of uses over the years. I put a two part epoxy on it when new and I would recommend the same or similar. Is this going to be a generic steel shed? You could do a raised floor on piers and no slab which is basically what mine is in some ways. With the cost of laminated beams and the ease of getting holes bored using a bobcat that might not be a bad way to go. Doing that would allow for underfloor dust extraction as well which might appeal to you...or not.

I would second the comment re underfloor dust extraction. If I were going to build a shed from scratch I would probably run some 150mm pipe under the base from the centre of the shed to my intended dusty location. So long as you can do this without comprising the strength of the foundation and in a way that doesn't interfere with vehicles driving over it.

Originally Posted by maxxsinner

Do you find the yellow tongue flooring slippery with a bit of saw dust on it Pat, or have you put a textured sealant on it? Do you happen to have pics of it on here?

I am very curious as I have been looking at getting my shed floor epoxied but the $$$$ have made me hold off. That and I am not sure it's the best solution. Putting down YT flooring is something I never considered but sounds like it has merit.

I have YT (not on concrete), and I coated it with water based Polyurethane. It can be slippery with dust, but not so much that I want to change it.

There is an up side to that - it encourages regular sweeping or vaccing although I'm not sure how Chistos feels about that.....

Certainly YT is easier on the feet/knees/back than epoxy would be. (if laid on battens).

[QUOTE=Beardy;2087473]Doesnt really make sense to pay an engineer to design the footings without giving the infill detail as well.
It is usually more cost effective and practical to pour the whole slab in one go as well but yes technically you are correct[/QU
A shed design usually comes with a footing design. It wouldnt be an extra cost. When submitting plans to council, the fee is calculated on the cost of the project. As the concrete slab will usually represent 50% of the project cost, it is a considerable saving to delete from spec. There is also a considerable labour saving as no formwork is required as the slab is poured inside the wall cladding. Best to seal the cladding to prevent concrete burn. This method also gives a vermin free finish between wall and floor.

same same I have worked on slabs that will crack before your eyes so controlling where you might get cracks only works where you expect pressure will occur such as where pipes are in place.I still say no matter how good you are at prep of slab if you can stop cracks from occurring you will be a rich man.

Step 1 Geotech report for soil classification (council will require this)
Step 2 Engineer designs slab but you have to tell him what type of activity /concentrated load points the slab will have imposed on it (referred to as dead floor load and live floor load)

General accepted practice for generic shed (domestic, double garage style) min 100mm slab with thickened edge beams and internal beam) 100mm 20mpa F82 mesh for a class M slab, class H usually has extra deformed steel in the beams and 25mpa concrete, H1 and above depends on geotech report and the reaction summaries as to what thickness, steel and mpa concrete required.

If you want to do under floor dust extraction, put ducting on top of slab, use appropriate joists and screw your sheet flooring down so if in the future if you change ducting configuration it is easy to get to.

As for the shed people that told you 75mm slab ok....BS !!!!

As with both Brett and Chris, yes the YT can be slippery when wet or dusty, good housekeeping is required. I'm a turner so very fine dust is present every day, so the dc and vax is used at the end of the day . . . normally with a beer in the other hand to balance myself

Originally Posted by rwbuild

Step 1 Geotech report for soil classification (council will require this)
Step 2 Engineer designs slab but you have to tell him what type of activity /concentrated load points the slab will have imposed on it (referred to as dead floor load and live floor load)

General accepted practice for generic shed (domestic, double garage style) min 100mm slab with thickened edge beams and internal beam) 100mm 20mpa F82 mesh for a class M slab, class H usually has extra deformed steel in the beams and 25mpa concrete, H1 and above depends on geotech report and the reaction summaries as to what thickness, steel and mpa concrete required.

If you want to do under floor dust extraction, put ducting on top of slab, use appropriate joists and screw your sheet flooring down so if in the future if you change ducting configuration it is easy to get to.

As for the shed people that told you 75mm slab ok....BS !!!!

Ray, why not a pier and beam floor/bearers/joists construction. Doing a slab, a good one not something just formed up and poured and then putting a floor on top with at least 200mm deep joists seems an expensive way to do it.

Gees, sounds more like a factory than a shed. But hey, its only money.

[QUOTE=rustynail;2087571]

Originally Posted by Beardy

Doesnt really make sense to pay an engineer to design the footings without giving the infill detail as well.
It is usually more cost effective and practical to pour the whole slab in one go as well but yes technically you are correct[/QU
A shed design usually comes with a footing design. It wouldnt be an extra cost. When submitting plans to council, the fee is calculated on the cost of the project. As the concrete slab will usually represent 50% of the project cost, it is a considerable saving to delete from spec. There is also a considerable labour saving as no formwork is required as the slab is poured inside the wall cladding. Best to seal the cladding to prevent concrete burn. This method also gives a vermin free finish between wall and floor.

The shed design comes with two options, one on pad footings for an earth floor and an alternate detail for a full slab with thickenings to support the structure
When you do the method you suggest without formwork what do you do the the back of your wall sheeting where it meets the concrete and what do you do with the base of your frame standard, do you frame them up on pedestals or concrete them in?
The hundred odd dollars in additional council fees would be insignificant to having two concrete pours and the additional work and concrete in having pad footings

I have a 100 mm slab and it has a 750 kg machine on it with no issues. The soil structure and type of soil does make a difference though - an active soil (like a cracking clay) needs a stronger floor. A soils engineer could advise but your local council will know if you need to worry about that.

If I were building a new shed for my workshop I would have an elevated floor so I could run my 150 mm dust collection ducting under it. That way it is easy to rearrange your ducting if you rearrange the workshop.

One of my machines has its main DC outlet low down and I end up with flex hose on the floor in one place (overhead everywhere else). It is very dangerous as a trip hazard. Alternatively, if you know where your machines are going to go you could dig 150 mm sewer quality PVC pipe into the ground before laying the slab and bring it up through the floor where needed.

Its a shed yes, cheaper insurance, no problems where you are going to put any machinery, uses and needs change over time, no restrictions if a slab, no rodent or termite problems, resale value is substantially more, nothing wrong with an infill slab either same result as integrated slab which still needs 100mm minimum and if the soil classification is H or above will move substantially more than an integrated slab. Not a lot of difference in cost between integrated slab (monolithic) and pier and infill slab.

You will also note that it is planed to use 1/2 for vehicle / trailer parking so no sense in 1/2 concrete 1/2 bearers and joists given the minimum legal requirement for clearance under bearers is 400mm which equates to 500 step from slab to floor. A total bearers and joist floor excludes vehicle access unless substantial increase in timber specification which would be 3 times cost of concrete.

The timber floor over slab is ONLY if doing under floor ducting for dust removal.

Originally Posted by rwbuild

A total bearers and joist floor excludes vehicle access unless substantial increase in timber specification which would be 3 times cost of concrete.

The timber floor over slab is ONLY if doing under floor ducting for dust removal.

My yellow tongue floor was engineered as a four car garage, the loaded wheel weight of a normal car is not that heavy. Some woodworking machines would weigh more.