House Extension Under Floor Heating - Are there any issues or problems?

Every man and his dog seems to have heard about the magical wonders of under floor heating and wants to incorporate it within their new house extension. Under floor heating for a house extension may be the fashion flavour of the decade at the moment but it is not the panacea of heating solutions as you may envisage. Underfloor heating systems can have many problems and issues on many levels.

Firstly, if you want to integrate under floor heating into your current domestic heating system then it is probably totally incompatible with that system.  This is due to the fact that under floor heating circuits require a much lower water temperature than that for the domestic wall hung radiators.

If this lower temperature is not achieved you will end up walking across the floor like a desert lizard not to mention the breakdown of the structural integrity of the floor over time.

Fortunately there are clever thermostatically controlled heating manifolds available that can do this magic trick of forming two temperature heating circuits from the one heat source (new or existing).

The second issue with underfloor heating systems is that they are not as instant as for wall radiators,  Heating up the thermal mass of the ground floor can take several hours and visa versa for cooling it down if it becomes too hot.  Having it on for longer periods at lower temperatures seems to be the way to go so it is not a switch on and off again system for sporadic intermittent use.

Thirdly, under floor heating can crack up the floor finishes.  I have seen many failures of cracked floor times where the floor screed has moved or expanded without proper design integration.  Without proper edge & threshold movement joints the floor will expand & crack.  Even screeding over the floor pipes without first pressurising them can cause massive cracking.

Our opinion is to avoid under floor heating for domestic house extensions.  They are great for new dwellings where everything can be designed from the ground up but their successes within the home extension market is very checkered and littered with horror stories.