Building an Extension Part 3 – Suspended Beam and Block Floor

Roger Bisby talks through the beam and block floor stage of building an extension.

Generally speaking there are two options for constructing ground floors. You can opt for a solid floor which involves laying wet concrete directly onto your ground surface or you can choose a beam and block floor which is also known as a suspended floor which allows you to achieve a low cost concrete floor.

Beam and block

Beam and block flooring can also be used for suspended flooring to subsequent levels and can even be used to support partition walling.

The advantage of a beam and block floor is that you don’t have to prepare the oversite saving time, materials and money because no hardcore or oversite concreting is required. If you’ve got an oversite which is a bit rough or spongy and you don’t want to compact concrete onto it you can simply put these beams over the top of it and it doesn’t matter what the ground does underneath so it’s great in clay or in made up ground.

It’s also a good system to use because it’s fairly cheap and as demonstrated it is quick and easy to install.

Other advantages of a concrete floor include a high thermal mass which can help reduce a building’s energy consumption as well as noise-reducing properties and fire-resistant properties.

This episode includes:

  • Raking out the oversite ready to lay the weed barrier and vapour barrier which stops the moisture coming up through the ground to the underside of the beams
  • Inclusion of air blocks underneath the beams
  • Putting the block into the beam – it’s important to clean the snots off the beams, sometimes you might need to use a brick hammer to scrape through
  • Why you need to run grout over the blocks, which is basically wet sand and cement which will fill in all the little gaps and tightens the floor up

Don’t forget to like the video if you want to see more like this.

About Roger Bisby

Roger Bisby is an English television presenter and journalist, known for his expertise in the British building industry.

One comment

  1. Hi Rodger,

    I am now planning on using a block and beam system in my garden room that is built from brick and thermalite blocks internally. My question is because the building is already built what would be the best method to install the beams? My thinking was doing a small strip foundation and laying block work for the beams to rest on or can I knock through the blocks to hold the beams up? from the ground I have about 4 courses of brick before reach dpc. Any advice is appreciated also il say the access is through the house or I would of went for a solid floor from the start but my joiner advised he would do it solid instead of timber frame I think this option is the best considering access.


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