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Impact-sound underlay is the quiet layer under every floating floor – it damps footstep noise and evens out tiny irregularities. This guide walks through it step by step – and shows you how to get the exact floor area before you buy.
Work out your material first →Underlay is sold by the roll or pack, and unlike planks it produces almost no waste – you simply need the floor area. Draw your room in the free planner and it gives you the exact square metres for your actual floor – then follow the five steps below to lay it.
Match the thickness and rating to your floor and subfloor, and pick a heating-compatible grade if you have underfloor heating. Unlike planks, underlay barely wastes anything – the amount you need is simply the floor area, which the free planner reads straight off your room.
The subfloor must be clean, flat and dry. Sweep and vacuum it thoroughly – grit, crumbs or a raised nail telegraph straight through a thin underlay and into the finished floor, so a spotless surface is well worth the few minutes it takes.
On screed or concrete, moisture can rise into the floor, so lay a vapour barrier first – or use a combined underlay that already has the barrier built in. On a dry timber subfloor you can skip it and lay the underlay on its own.
Roll the strips out edge to edge and tape the seams – never overlap them, because a double layer makes a ridge that telegraphs into the floor above. Run the strips perpendicular to the plank direction so the joints never line up.
Cut the underlay to the walls, leaving room for the expansion gap the floating floor needs. Then lay the floor straight on top – the underlay stays loose underneath, held in place by the weight of the planks.
Underlay barely wastes anything, so all you need is an accurate area. The free planner reads the exact square metres off your room, so you buy the right number of rolls or packs – no leftover, no second trip.
Open the free planner →