What kind of base do you need for a Garage blog feature image

What kind of base do you need for a Garage?

NattyShedGirl Buyers Prep, Garage Buyer's Guide, Garages Leave a Comment


Garages don’t have floors, so they need a concrete plinth to sit on. This is where most people who are thinking about buying a Garage start to ponder.

“Okay so I want a Garage, but I need to have a base first…”

Oh, Shedlord – what now?!

Well, the plinth needs to be strong enough to carry the weight of the walls and the roof, as well as whatever you’d like to put in it.

It also needs to be a certain size, made from the right stuff, be in square and BANG ON level.

Not asking for much right?

Way back, in the beginning, Garage bases were always a nightmare to organise. So bad in fact, we had to start making them ourselves.

Ludicrous! A joiner making a Garage base? Yep. It happened.

Three things we know about Garage bases

1. Excavation

If your existing site is MENTAL unlevel, you have horrendous access and a terrain soft as butter, then it’s going to take a lot of preparation before we get anywhere near the concrete.

If your Garage is where ‘normal’ people have their garages, to one side of the house, already level AND in good standing firm ground, then you can put the kids’ university funds away! We’re going to have an easier ride here.

what kind of base do you need for a garage - mental site


what kind of base do you need for a garage - easy rider site


2. Sub Base

Once the area has been excavated we’ve got some serious jobs on.

Depending on the ground condition you can expect to lay a minimum depth of 100mm of T1 hardcore. Once this is compact and level you would lay a DPC (damp proof membrane) before the concrete gets poured.

What kind of base do you need for a Garage - sub base

Schematics of a sub base

3. Concrete

I like to call this the list of three to concrete perfection:

  • To Size
  • In Square
  • Level

Not all base layers appreciate our method. Some like to make the base bigger than the Garage.


Don’t do that.

To Size

Before concrete is poured there’s a timber frame built to shutter the concrete in – this is where the measurements are so CRUCIAL!! Setting up the formwork takes precision and close attention to where you’re measuring from.

If your base is not to size then we cannot slot the walls over the sides allowing the water to drain away from the building properly.

In Square

Keeping your base ‘in square’ keeps the building in square. How you do this is by using the corner to corner measurements.

Finally… a use for all that geometry you learnt at school! The square is imperative to how the building goes together. If your base is not square, Dom will have to ‘THROW’ the panels which isn’t nice to see, nor is it a pretty finish.


Some base layers cannot fathom the prospect of not having a ‘run’ on the level. A run on a base is typical to allow water to run away. Our Garages do not want a run because they don’t leak so there’s no water. This is common on hard landscaping but is definitely not welcome on a garage base.

LOOK?! Isn’t she beautiful?

What kind of base do you need for a Garage - concrete garage base

Concrete Garage Base

Now I know what you’re thinking… I cannae do that?!

You’re right, so please, for all the Shed love in the world, do not try it – unless, of course, laying concrete is your actual job.

At G&M we only work with amazingly handsome and clever trades. Thankfully we know just the team to kit you out with a magnificent Garage base.

We recommend McNiven Construction for all our concrete bases. We love McNiven because they know what we’re talking about. They are kind and thoughtful when dealing with our customers, and they get the job done when they say they will, with the utmost precision.

So, there you have it Sheddies! A Garage is only as good as the base it stands on – so be sure to get it right.