Insulating roof support assembly, a method of installing such roof support assembly and an insulating roof construction

Abstract

The present invention concerns an insulating roof support assembly for a roof structure comprising a plurality roof elongated rafters spaced apart in a predetermined distance with insulation boards therebetween, wherein elongated mineral wool fiber insulation elements are provided on the top of each of the elongated roof rafters and elongated wooden elements on top of said insulation elements with at least one impermeable membrane between at least two neighbouring insulation elements sandwiched between the wooden elements and the insulation elements.

Claims

1. An insulating roof support assembly for a roof structure, comprising: a plurality of roof elongated rafters spaced apart by a predetermined distance; with insulation boards disposed between the plurality of roof elongated rafters; an elongated insulation element disposed on top of each of the elongated roof rafters, the elongated insulation elements each having a width that is the same as a width of the elongated roof rafters and parallel thereto; elongated wooden elements disposed on top of said insulation elements; at least one flexible membrane for waterproofing extending between at least two of said insulation elements, the at least one flexible membrane being sandwiched between the wooden elements and the insulation elements.

2. The insulating roof support assembly for a roof structure according to claim 1, wherein the insulation boards have a total thickness that is the same as the combined thickness of the elongated roof rafters and the elongated insulation element.

3. The insulating roof support assembly according to claim 1, wherein the elongated insulation elements provide a compression strength at 10% strain (CS(10)) in the range of 15 kPa to 30 kPa.

4. The insulating roof support assembly according to claim 1, wherein the membrane provides a specific variable diffusion-equivalent air layer thickness (sd-value) of 0.01 m.

5. The insulating roof support assembly according to claim 1, wherein the wooden elements, the at least one membrane and the elongated insulation elements are mounted to the elongated rafters by a plurality of fastening members.

6. The insulating roof support assembly according to claim 1, wherein the elongated insulation elements are made from mineral wool fiber material.

7. The insulating roof support assembly according to claim 6, wherein the mineral wool fiber insulation elements have a density of 70 kg/m.sup.3 to 100 kg/m.sup.3.

8. The insulating roof support assembly according to claim 6, wherein the Lambda declared values are: approx. 0.12 W/mK for the roof rafters; approx. 0.034 W/mK for the spacer elements; and approx. 0.034 W/mK for the insulation boards.

9. The insulating roof support assembly according to claim 1, wherein the roof structure is an inclined roof.

10. The insulating roof construction for buildings comprising a roof support assembly according to claim 1.

11. The roof construction according to claim 10, which has a total U-value of 0.12 W/m.sup.2K.

12. The insulating roof construction according to claim 10, wherein one or more insulation boards are provided in a space between the rafters.

13. The insulating roof support assembly for a roof structure according to claim 1, wherein the elongated insulation boards are further disposed between the elongated insulation elements.

14. The insulating roof support assembly for a roof structure according to claim 1, wherein the insulation elements have a density greater than a density of the insulation boards.

15. A method of installing an insulating roof support assembly, said method comprising the steps of: on a plurality of roof elongated rafters spaced apart by a predetermined distance, providing an elongated insulation element on top of each of the elongated roof rafters, the elongated insulation elements each having a width that is the same as a width of the elongated roof rafters and parallel thereto; and providing elongated wooden elements on top of said insulation elements with at least one membrane extending between at least two neighboring insulation elements and sandwiched between the wooden elements and the insulation elements.

16. The method according to claim 15, further comprising mounting the elongated insulation elements on the top of the rafters off-site.

17. The method according to claim 9, further comprising mounting the support roof assembly on the roof rafters for refurbishment of an existing roof construction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the invention is described in more detail with reference to the accompanying drawings, in which:

(2) FIGS. 1 and 2 are cross-sectional schematic views of roof constructions according to the prior art;

(3) FIG. 3 is a schematic side view of an insulating roof support assembly according to an embodiment of the invention;

(4) FIG. 4 is another embodiment thereof;

(5) FIG. 5 is an exploded schematic front view of the insulating roof support assembly;

(6) FIGS. 6 and 7 are two variants thereof where the insulation roof support assembly is assembled; and

(7) FIG. 8 is a schematic cross-sectional view of the roof support assembly of example described below.

DETAILED DESCRIPTION OF THE INVENTION

(8) FIGS. 1 and 2 show examples of known roof constructions. In FIG. 1, a number of wooden roof rafters 1 have been extended with additional wooden rafters 1. Membranes 4 are fitted around the rafters and insulation boards 2 are then fitted between the rafters 1, 1 and a second membrane 4 is then provided on top of the rafters 1, 1. The roof top structure is then mounted, i.e. the wooden support members 5 and the horizontally oriented laths 6 with roof tiles 9 or the like on top. In FIG. 2, there is no extension of the rafters 1 but instead a second layer of insulation 2 is provided.

(9) FIG. 3 shows an embodiment of the invention, where a roof rafter 1 is provided with an elongated mineral wool fibre insulation element 3 on the top of the rafter (see also FIGS. 5-7). A flexible membrane 4 for waterproofing as it has been described before is provided on top of the elongated insulation element 4. A wooden support member 5, e.g. a Kerto board is then placed above the insulating spacer element 3 thereby clamping the membrane 4 between the insulation spacer 3 and the support member 5 when the assembly is mounted via glue and/or fastening screws 8 (see FIGS. 5-7) penetrating the membrane 4 and the spacer elements 3. On the support members 5 a number of horizontally oriented laths 6 are provided onto which the roof cover (not shown) can be mounted.

(10) The rafters 1 and thereby the roof construction are fixed to a wall plate 7 on the top of the wall of the building.

(11) As shown in FIG. 4, the insulating roof support assembly according to the invention may be mounted on rafters 1 of an existing roof construction. The mineral wool fibre spacer elements 3 may due to their resiliency absorb any unevenness 1a on the top surface of the rafters 1 so that when the spacer elements 3 are mounted the top wooden member 5 becomes aligned with the roof inclination. Said spacer elements 3 are mounted together with the support members 5 and the membrane 4 via fastening screws 8 as described before. In case of considerable unevenness 1a of the rafters 1 it might be adequate to apply additional flexing to the bottom part of the spacer elements by means per se known in the art to influence the resiliency to the extent needed. This extra flexing for refurbishment situations makes the roof support assembly according to the invention particularly advantageous.

(12) The mineral wool fibre spacer elements 3 advantageously provide a very low thermal conductivity, expressed as the Lambda declared value according to EN13162 of between 0.030 W/mK and 0.035 W/mK, preferably of about 0.034 W/mK.

(13) As indicated in FIGS. 6 and 7, insulation boards 2 may be provided between two adjacent rafters 1 with an insulating spacer element 3 mounted thereon. The insulation boards 2 may be traditional low-density mineral wool insulation boards as they are commonly known, being installed in one or more layers in order to provide the predetermined thickness of the thermal insulation required for the roof system.

(14) The rafters 1 are normally made of wood and are normally part of the roof construction sections. When providing a roof construction to a new building, the insulating spacer elements 3 may advantageously be mounted as extensions on the rafters 1 during the production of the rafter sections. Advantageously, the insulating spacer elements 3 are provided with the same width dimensions as the rafter 1 (as shown in FIGS. 6 and 7). This makes the fitting of the insulation boards easy and simple.

EXAMPLE

(15) The main purpose of the roof solution in a modern building is to have a balanced and efficient thermal performance defined by the U-value or overall heat transfer coefficient. This value indicates the rate of heat transfer through a specific component over a given area if the temperature difference is exactly one degree (1 Kelvin). The measurement unit of the U-value is therefore W/m.sup.2K; the smaller the U-value the better the level of insulation.

(16) With a system according to the invention it is found possible to complete a coherent un-broken fibrous insulation shell. A shell ensuring that the buildings structural parts are efficient protected and thermally well insulated. The building envelope does not impair the thermal performance significantly, except for those necessary penetrations that must be handled separately.

(17) As an example of the thermally insulated roof support assembly, shown in FIG. 8, the system is made of components described below.

(18) Wooden rafters 1 are provided at an axial distance (L.sub.1) of 1.000 mm, having a density of approx. 500 kg/m.sup.3, and with a width of 45 mm, a height of 180 mm and a Lambda value of 0.12 W/mK (at approx. 12% moisture content).

(19) The spacer elements 3 on top of rafters 1 are made of mineral wool fibres with a density of 90 kg/m.sup.3 and with a width of 45 mm, a height of 180 mm and a Lambda declared value of 0.034 W/mK according to EN13162.

(20) The intermediary insulation boards 2 are of the type Super flexibatts produced by Rockwool A/S and with a thickness of 180 mm (T.sub.i) and a Lambda declared value of 0.034 W/mK according to EN13162.

(21) The rafters 1 are provided on a layer of wooden fibre boards 10 of the OSB type having a density of approx. 650 kg/m.sup.3, a thickness of 12 mm and a Lambda value of 0.13 W/mK.

(22) By choosing the above described design and the said materials, the total thickness of the roof support is 372 mm in order to achieve a total U-value of 0.10 W/m.sup.2K.