Home DIY - Wall Insulation

In older wood-framed houses where insulation is virtually non-existent and the dismantling of the wall to install conventional fiberglass batting would be prohibitively disruptive and expen­sive, the use of blown insulation can be very effective. This can be carried out only by experienced professional operators with the appropriate equipment.

On a clapboard house, a row of clapboards is carefully removed at the level of the sill and top plates and a 1in diameter hole is drilled through the sheathing between each stud. The insula­tion - either cellulose or fiberglass - is then blown into the voids between the studs, where it settles into a solid layer and dramatically reduces heat losses through the house walls. Once installation is complete the clapboards are replaced, leaving virtually no evidence of any disturbance. This method can also be used to fill between the joists in the attic.

If your house has masonry cavity walls, then the simplest method of insulation is again to have the cavity filled. The process is not a do-it-yourself job and the installation should be tackled by a specialist company.

Houses with solid walls can be insulated externally, but more often the job is done working on the inside of the house. There are various methods and the one to choose depends on whether you want to retain the impression of a solid wall or prefer a decorative finish of cladding or paneling.

Using paneling

Another method of insulating old masonry walls is to panel them. You can use tongued and grooved boards or large decorative Masonite panels. Either material is quite straightforward to fix and has the dual function of being decorative as well.

Wall boards are available as either V-jointed boards in knotty pine or cedar or as pine shiplap. The boards are fixed to 1 1/2 X 1in sawn softwood support strips, which are fixed at 16-20in centers for 1/2in thick boards and 20-24 in centers for 1/2in thick boards. They can be fixed horizontally or vertically.

You must allow for a slight gap behind the boards to enable air to circulate. This will be achieved automatically where the support strips are fixed vertically. With horizontal fixing, use packing pieces behind the strips. Then add insulation material between the strips.

The boards can be fixed by nailing through the faces and punching the heads below the surface. Make sure you fill the holes after­wards. An alternative is to use very thin firdsriing nails through the tongues at an angle so that they are covered by the next board. The other option is to use special metal clips. Tap the boards firmly together as you fix them, using a wooden block between the edge and the hammer head as protection.

To finish off at ceiling level, fix quadrant molding to conceal the sawn board edges, remembering to leave a small air gap. At the bottom, you can either leave a small gap as well or fit a new baseboard.

To fit decorative panels, you need vertical support strips to provide a fixing for each edge, plus horizontal battens at 16in intervals. If the corners are out of true, leave a small gap so that the board is positioned horizontally. You can cover this later with a piece of molding. Again leave a small gap at the bottom for possible expansion and cover this with baseboard.

After fixing insulation between the supports, you can secure the panels either with pins (punched below the surface with holes filled) or with adhesive. Pins are really only suitable for boards with vertical grooves that resemble plariking, since they can then be easily con­cealed within the grooves.

Where you are using wall panel adhesive, apply a generous layer to the supports and press the boards firmly in place. If a wall is perfectly flat, you can fix the panels directly .to the wall surface.

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Comments 1 comment

Dave 5 years ago

This is a really good blog. I had someone come over a asses my home and was told that before I put it up for sale, better insulation would up my house valuation so I just wanted to get a better understanding of what it involved. Really good post, thanks.

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