In every house stale, moist air must be removed and replaced with fresh air from outside. This happens not only in an obvious way when a window is opened or an extractor fan switched on, but all the time. For example, air passes up chimney flues, or finds a way out through the inevitable small gaps in the house structure.
Unless power ventilated, most modern houses have very little chance of such natural ventilation because improved standards of insulation and draught proofing have made them much more airtight than formerly.
Decide on the fan position, and then mark the outline of the ducting on the wall outside. Drill holes right through the wall to mark it on the inside as well.
The heating hills and keeps the house’s occupants warm and comfortable. The danger, however, is to prevent the occupants creating too much moisture for the air to hold. If this happens, condensation will be the inevitable result, and extra ventilation will then be needed.
This reduction in natural ventilation not only causes trouble within the house, it can also affect its structure. Two particular problem areas are roof spaces and under-floor voids. To prevent it, more ventilation must be provided via ridge and eaves-level vents in roofs, and air-bricks in walls.
- Decide on the fan position, and then mark the outline of the ducting on die wall outside. Drill holes right through the wall to mark it on the inside as well.
- Drill a series of closely spaced holes through the wall from inside, working within the guide holes drilled from outside. Repeat on the wall outside.
- Chop out the brickwork with a wide bolster (stone-cutter’s chisel) and club (spoiling) hammer, again working from inside and outside the house.
- Use ducting for a cooker (stove) hood with a short length of pipe, then use connectors as required connecting the hood to the outlet.
- Wall-mounted fans usually need a round hole. Cut it out, line it with a short length of sleeking and make good around it inside and outside using plaster.
- Fit the fan into the sleeking, ready for its electrical supply to be connected. Put a cover grille to the outside end of the fan ducting.
For ventilating rooms, what is needed is some controllable means of getting rid of excess moist air without wasting too much valuable heat. In habitually steamy rooms such as kitchens and bathrooms, an extractor fan is the best solution. It will extract the moist air quickly, and will also help to get rid of unwanted smells.
In other rooms, it is worth considering fitting small ‘trickle’ ventilators at the top of window frames and putting in extra airbricks, as these will often supply enough ventilation to allow the moist air to disperse before condensation becomes a problem.
Fitting Extra Air-bricks
- Air-bricks are available the same size as one, two or three bricks. To fit one, start by drilling a series of closely spaced holes through the wall.
- Use a club hammer and a bolster (stone-cutter’s chisel) to cut out the brickwork. With solid walls, drill holes right through and also work from inside.
- Fit a cavity litter if the wall is of cavity construction, and then carefully trowel a bed of fairly wet mortar on to the bottom of the opening.
- ‘Butter’ mortar on to the top of the air-brick and slide it into the opening. Push Mortar into the gaps at the sides and park it down weld
- Use drier mortar to point neatly all around the air-brick. Inside, make well the wall with plaster and cover the opening with a ventilator grille.
- As an alternative to a terracotta air-brick, fit a plastic type. Interlock the sleeves to the hole as the two parts are pushed together.
- Slide the outer section into place, and point around it. Then slide the inner section in place from inside the house, and fit its cover grille
Airbricks are available the same size as one, two or three bricks. To fit one, start by drilling a series of closely spaced holes through the wall.