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So - Attempt #1 of trying to build my house failed - Made Ground (Poor soil bearing), a buyer who wouldn't grant me legal permission to access the mains water after I sold and changed their mind after I'd let go all the builders, and my planning permission extension was refused. Attempt #2: Re-Applied for Planning permission from scratch - preliminary decision due July, final decision August 2023. Place my house back on the market in the meantime somewhere between those two dates. Finally I need to find a solution for the poor soil / made ground. Today was that day! The Structural Engineer got the Ground Screw company to come onsite and put a 1.5 meter screw into the ground in 5 different places and do a pull test against each one. They each held over 4 tonnes of pull pressure which is good and the results will inform the Raft Design so I can get it priced. It was all done with hand tools with a motor assisting the Screw insertion / extraction running on 240v via an Extension lead. Then they put a tripod above the screw and a measurement device to determine the force trying to pull it out. Probably looking at 30 or so Ground Screws and a number of Screw Piles for point loads & using a laser level. Had a good chat with the team and they have 5 years of experience and have been to Holland where they source their system from. Due to the coastal conditions there they typically use 6 meter screws! Some soil conditions eat away at screws over time 30-40 microns per year which gives you 50 years guarantee on a 3mm thick screw to allow up to 1500 microns to be eroded. They had heard about some cheaper Chinese screws that were pulled after 3-4 months for a different reason and they had started to rust as their galvanisation was not thick enough. Very bad if that happens! The team do a lot of extensions, shipping containers and garden rooms but houses too. If the screw is exposed more than 500mm you need bracing - this can happen if the ground is sloped. The system should save on soil muck away and concrete costs hopefully. Cost wise I'm looking at @ 5K for the ground screws vs digging 2.2 meter strip foundations and muck away costs / concrete as the alternative. You can sit a foundation on top of the screws and this may mean you don't need a Radon barrier as there is airflow underneath? I'll go with whatever the Structural Engineer recommends though. Anyway, thought I'd have a big JCB onsite but this took about 4 hours with powered hand tools and gave me confidence in the system and the team behind it which helps. Educational Day all in all!!

We are building a 30m2 timberframe single storey annex and want to minimise our use of concrete. We want to include a wet underfloor heating system. For the flooring we are thinking the layers would be: compacted ballast compacted sand PIR insulation board UFH pipes screed wooden flooring Thinking that we don't need a concrete slab for stability because if it shifts a little and the screed cracks the wooden flooring will cover over those defects. The question is how to constrain the flooring? Can you use blocks without foundations, but supported by earth on the external side, to create the footprint of the building and then compact and build up the flooring within the fooprint? The timberframe structure can be supported by ground screws. All the examples of using ground screws that I've seen have the building suspended slightly above the ground - is that essential? Can you position the ground screws so that the base of the timber frame sits ontop of the footprint blocks but the weight is supported by the ground screws? Is there a better way to combine a single storey timberframe build with a solid floor whilst still using minimal concrete?

Many thanks for the superb advice I have received on this site so far. It has been amazing. Has anyone had any experience using ground screws for the foundations of a garden office? Any advice would be greatly appreciated.