Heating and Plumbing for a House Extension
Extending a house adds floor area the existing boiler was never sized for, and usually means new radiator or underfloor circuits, a soil pipe extended further from the stack, and a fresh look at whether the current system can cope..
Extending a house adds floor area the existing boiler was never sized for, and usually means new radiator or underfloor circuits, a soil pipe extended further from the stack, and a fresh look at whether the current system can cope.
Rechecking heat loss for the whole house
An extension changes the total heat demand, so the existing boiler's output needs checking against the new floor area rather than assumed to be adequate.
Extending drainage runs
A rear or side extension often means the soil pipe has to travel further to reach the existing stack, and fall and access for rodding both need planning properly.
Underfloor heating on the new slab
Many extensions use underfloor heating on the new floor while the rest of the house keeps radiators, which means a manifold and a second flow temperature to manage.
Plan the plumbing for your extension
Send us the extension plans and the current boiler make, and we'll confirm whether it copes or needs upgrading.
Questions we get asked
Will my existing boiler cope with the extension?
Sometimes, if it was already oversized, but we check the sums rather than assume — undersizing shows up as slow warm-up, not obvious failure.
Can radiators and underfloor heating run off the same boiler?
Yes, with a manifold and blending valve to give the underfloor circuit its own lower flow temperature.
When should plumbing be planned in the build?
Ideally before first fix, so pipe and cable routes are agreed before walls and floors close up.