Underfloor Insulation - Standing Comfortable

In cold months, do your floors feel cold? In all probability, there is no underfloor insulation between you and your unheated basement or crawlspace. Your floor belongs to the three most important places in your home that needs insulation (with the roof and the walls being the last two.)

In general, floors are either solid, or concrete slabs, or suspended timber floorboards on joists. Insulating a solid floor is more difficult (and expensive) than insulating a timber floor. (Payback for concrete is 8 to 10 years while timber floor insulation has 3 to 5 years.)

Wooden floor insulation

If you have access from below, it is easy to stuff the insulation between the joists. You can also add more insulation than the depths of the joists can permit. You can add battens to the underneath of the joists and fastening the second layer of retaining boards, fabric or netting to them.

Insulation should be installed all the way back at the end of each joist run so it can touch the band joist. Usually, there is a narrow joist space on the walls that is parallel to the joist. The insulation should be cut to fit this space.

Holes

You need to be sure that holes in the floorboards where pipes and other wires pass, plus the gaps around the edges and between floorboards have to be plugged with mastic and tapes to prevent draughts.

There are often both pipes and wires in crawl spaces under floors, and occasionally there will be a junction box. You may need to cut or split the insulation to fit it around electrical wiring, boxes and drain pipes. Never leave voids (un-insulated spaces) nor overly compress the insulation.

Use nylon banding or metal insulation support. If there is a possibility of the room being flooded, the damp proof layer should not be placed between the insulation. Instead, there is need to use draught-resistant fabrics which the water can drain away.

Insulating concrete floor

If there is an excavation or a floor is replaced, this is an opportune time to improve the standard of insulation.  If you place the insulation above the slab, the room will warm up faster when the heating is switched on. It also cools down fast.

Likewise, it will also affect the floor level. This has an impact on door openings, stairs and other previous fixtures. In this instance, the phenolic foam is the most common solution, because it can achieve greater insulation for less depth.

Below the slab

Insulation below the slab is generally better especially in south-facing room since the concrete helps absorb heat and limits the overheating. Here the damp proof membrane goes above the concrete. the moisture-resistant chipboard goes on top beneath the flooring surface.

Insulation goes on top of this and around the edges and concrete is poured on top of all that. If the underfloor heating is used, which is fixed to the top of the concrete mix, a small amount of concrete is poured on top. Underfloor insulation takes a bit of work since there are choices to be made.