Kooltherm K7 - Over Rafter Layer of Insulation
Over rafter insulation without a sarking board is simply fixed by placing the Kingspan K7 Pitched Roof Board over the rafters and under 38 x 38 mm treated softwood counter–battens in line with the rafters. Secure the counter–battens to the rafters by fixing through both the counter–battens and the K7 Pitched Roof Board.
Over rafter insulation with slates fixed directly into a sarking board is simply fixed by placing the Kingspan K7 Pitched Roof Board over the rafters with the sarking board overlaid. Secure the sarking board and K7 to the rafters by fixing through both the sarking board and the Kingspan K7 Pitched Roof Board.
Over rafter insulation with a sarking board and tiles on tiling 1 battens and counter–battens, is simply fixed by placing the K7 boards over the rafters with the sarking board overlaid, and with 38 x 38 mm softwood treated counter–battens in line with the rafters.
Secure the counter–battens to the rafters by fixing through the counter–batten, the sarking board and the K7 board.
The K7 board should be tightly butted. Boards may be laid either across or down the line of the rafters and should preferably be laid break bonded in order to help improve the racking strength of the roof. All board joints running from eaves to ridge must occur over rafters.
There is no necessity to tape board joints. A preservative treated stop rail should be secured to the rafters close to the eaves.
Fixings for Over Rafter Insulation
Helifix In–Skew, Target Skewfast, Wallfast Timfix or similar approved fixings should be applied at centres appropriate to the design of the roof and location of the building.
Kingspan K 7 - Between Rafter Layer of Insulation
Between rafter insulation can be installed by three methods.
In cases where the insulation between rafters is to be flush with the top of the rafters but does not fill the full rafter depth, install the insulation by the use of nailable sarking clips.
The nailable sarking clips are driven into the upper surface of each rafter at one–metre intervals up the roof slope.
The nailable sarking clips then support lengths of Kingspan K7 Pitched Roof Board suitably trimmed to size and placed between the rafters.
In cases where the insulation between rafters is to be flush with the bottom of the rafters but does not fill the full rafter depth, install the insulation with the aid of battens nailed to the side of the rafters.
The battens should be in the appropriate position to ensure the insulation is flush with the bottom of the rafters.
In cases where the insulation between rafters fully fills the rafter depth, simply install the correct thickness of insulation in such a manner that it is flush with the bottom of the rafters.
In all cases, ensure that insulation boards are tightly butted and that there is a tight fit between the insulation and the rafters.
Fill all gaps with expanding urethane sealant.
Under Rafter Layer of Insulation
Please refer to Kingspan Kooltherm K18 Insulated Dry–lining Board page. Click Here.
Breathable Sarking Membrane
The specified breathable sarking membrane (such as Dupont Tyvek Supro) is applied as specified. Application advice should be sought from the appropriate membrane manufacturer.
In cases without a sarking board, the sarking felt is draped over the rafters to provide a channel for water drainage and held in place by the slate / tile battens, which are nailed through the felt to the rafters.
In cases with a sarking board, the sarking felt is applied over the sarking board and held in place by the slates or counter–battens which are nailed through the felt to the sarking board.
Kooltherm K7 - Slating and Tiling
Slating and tiling over K7 Pitched Roof Boards is exactly the same as on any other pitched roof except that in some instances the slate / tile battens are fixed to the previously applied counter–battens. It is, however, essential that slate or tiling rubble does not lie in contact with the breathable sarking membrane (if used) as this may allow wind driven rain or melted snow to penetrate the breathable sarking membrane.
K7 has a foil faced durable surface and no further treatment is necessary. However, K7 is not intended
to provide an internal finish and should be underlined with a suitable building board.
Cutting should be carried out either by using a fine toothed saw, or by scoring with a sharp knife, snapping the board over a straight edge and then cutting the facing on the other side.
Ensure accurate trimming to achieve close–butting joints and continuity of insulation.
Daily Working Practice
Installed Kooltherm K7 boards should be protected against inclement weather.