Concrete Lintels

[adrian.groves]

Hi,

I am building the foundations for a garden office of 3.8m by 3.9m footprint

Access to the site is not great (approx 70m walk with wheelbarrow and rising about 5m) so I want to use materials that I can carry up a little each evening. This rules out a concrete raft so I am considering supporting the floor on concrete lintels placed perpendicular to the floor joists at approx 750mm centres.

Can anyone tell me if concrete lintels are generally straight or have a bow built in and whether there is likely to be much flex under the floor.

Thanks
Adrian

 

[Notch7]

What are the supporting walls? Can they not take the floor joists?

Im not seeing why you need, supporting walls, lintels and joists.

At 750mm centres may you only want small section floor joists, but if you dont have 65mm lintels youve got extra height

12 lintels would be a fair weight to move, nearly 30kgs each

 

[adrian.groves]

Thanks Notch 7.

The floor joists are only 2" by 2" timber to lift the building clear of the floor, hence the need to support them regularly.

My thinking was that rather than build 7 walls I could use the lintels supported at either end.

 

[cdbe]

As above, why not a suspended timber floor - treated 8x2 at 400 centres would be fine (or 4x2 if you split with a sleeper wall. If you're planning on heating it you'll want insulation between the joists. You should have a layer of oversite concrete (to cover the soil under the floor) but would get away with a few layers of DPM polythene held down with bricks, stone or whatever you have lying around. You'll need a few air bricks or vents to ventilate the void.
Also, although it probably wouldn't matter, the thin lintels are generally designed to work with courses of brickwork above then.

 

[adrian.groves]

I didn't make it clear in my post that the office is a log cabin style.

I was trying to keep the total height low, but I think throwing out the bearers that come with the cabin and buying new 4" joists with 1 wall across the middle would work

 

[Notch7]

Im building a summer house / garden studio at the moment.

Having played around with various options, I decided to dig out 3 parallel trenches and cast some concrete pads. Ive done that and am now digging out some of the soil in between so its about 100mm lower than the concrete, for air flow. My floor joists will be 5 x 2.

Its quite tricky to keep below 2.5m if needed to be PD.