Alternative foundation design for buildings close to trees Presented by Alan Osborne Interim Managing Director on 5 th February David Highton Area Manager on 12 th February

Site Investigation Don’t underestimate the value of site investigation Whatever the size of the project !!!! LABC Warranty gives you access to tools allowing you to calculate/determine the required depth of foundations in clay sub-soils in close proximity to trees

Deep strip foundations If you know what to expect before commencing work other foundation types/designs may be more cost effective Especially where foundation depths are in excess of 1.5m

Specialist designs Bespoke design by structural engineer(s) Propriety systems – hand over to company/organisation to design and prove to Building Control

Raft v Piles A raft spreads the loads over the footprint of the building and allows the designed building to withstand seasonal movements keeping the structure above the raft stable

Raft v Piles Piles transmits the buildings loads to depths below the area of influence the tree(s) could cause problems. Reinforced ring beams between the piles, like raft foundations, are designed to withstand the effects of seasonal movement

Designed prior to commencement Both offer potential overall cost savings if designed prior to commencement Less disruption on site Speedier construction Reduced amounts of spoil to be remove from site

After the event Alternative designs often impractical once foundations have been excavated, due to time delays associated with getting a foundation designed and approved by Building Control.

Extensions Same potential for cost savings if foundation design is considered prior to commencing work, Ensure all connection points between new and proposed work are fully designed to ensure adequate and appropriate movement joints and provided throughout.

Things to lookout for when pricing Are there trees visible, if you have to crank your neck there are likely to be problems irrespective of soil condition If there are no site investigation reports seriously consider trial holes to check for clay If clay is present you will need to identify the tree species

Carry out a quick check Ascertain the distances the trees are from the work Determine the type of tree(s) Satisfy yourselves as to the type/grade of clay (low, medium and high shrinkage) As a result of the previous presentations you should now be in a position to calculate depths yourselves

Thank You Any Questions