Raft foundation pumping

15 Oct 2009
Reaction score
United Kingdom
Hi all

I am having a reinforced concrete raft foundation laid on poor ground conditions. It is 35 feet square. The raft platform is 6 inches thick and the beams are a further 12 inches deep with bottom widths varying from 3 feet to 18 inches and their top widths being another 12 inches. i.e 45 degree angles for base of beam. I thought the best way to lay it would be to excavate the entire area of the raft to 15 inches; infill with required material; compact that infill; then excavate the beam regions (removing both infill and underlying clay as required); infill and compact under the beam bottoms; place reinforcement cages (pre-fabricated with bent bars and mesh) securely on "chairs"; place the required mesh securely in the platform area; then pump the concrete in. I foresee a possible practical problem in levelling the surface over such a wide area but cannot see how the beam regions can be laid other than at the same time ( problems with sectioning off the reinforced sections.)

My groundworker wants to excavate the beam regions before laying the infill and pour the concrete in to the first 12 inches of of the beams using shuttering (which will leave 5 inches of the cages protruding upwards) and then put in the main platform infill ; place the platform reinforcement mesh and pour the concrete in one half of the raft at a time, enabling him to level the surface more easily.

Can anyone advise me please?

Many thanks,
Sponsored Links

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local