Subfloor Ventilation Improvements in Newcastle & Tynemouth

Why subfloors need air

Many older homes in Newcastle and along the coast have suspended timber ground floors, where the floor boards sit on joists above a void. Air bricks in the outside walls let air flow through the void and carry moisture away. If those vents are blocked or the air cannot circulate, the timbers stay damp, which encourages wet rot and other decay.

What goes wrong

• Air bricks buried by raised ground levels, paths or patios
• Vents blocked by soil, debris, paint or past building work
• Internal walls or sleeper walls without gaps, stopping air crossing the void
• Extensions that closed off vents on the original wall
• Water from leaking pipes or drains collecting in the void
• Bare soil under the floor that gives off moisture

Typical improvements

Which measures are appropriate depends on the building, so we start with an inspection through floor hatches or lifted boards, checking vent positions, timbers and moisture sources. Improvements can include:

• Clearing and replacing air bricks, and lowering external ground levels where needed
• Adding more air bricks to give a through flow of air
• Fitting ducts where airflow has to pass an extension or solid obstruction
• Forming openings in sleeper walls so air crosses the whole void
• Clearing debris from the void and covering exposed soil with a suitable layer
• Fixing leaks and drainage problems that add water to the void

Things to avoid

Do not block vents to make a room warmer. Also be careful with insulation, which can change how moisture behaves in the void. Where insulation is being added under a floor, ventilation should be kept up.

Linked repairs

Where timbers have already decayed, see timber floor joist restoration. Wet conditions in the void may come from drains, see underground drainage repairs. Ventilation changes usually need no planning permission, though Building Regulations guidance on floors is at GOV.UK.

Frequently asked questions