GB2485809A - Damp proof layer for use between timber frame and hard standing - Google Patents

Abstract

The damp proof layer 1, primarily for supporting the timber frames of buildings above their hard standing, comprises a layer which a continuous surface which includes raised and lowered portions. The layer is preferably in the form of a strip with a first flat surface and a second surface which may be corrugated or alternatively have raised indentations that may have a triangular profile in one direction. The raised indentations may have a triangular profile in a second, orthogonal direction so as to form pyramids, the apexes 14 of which may be flattened. The layer may also include holes. The layer may include or be formed from plastics, preferably polyurethane. Also claimed is a method of fabrication.

Description

DAMP PROOF LAYER AND SYSTEM

Field of Invention

The present invention relates to the construction industry, and in particular the construction of timber framed buildings.

Background of Invention

With increasing concerns over fossil fuel use, sustainability and local energy production, sustainable and efficient construction methods and materials are highly sought after.

Wood or timber is one of the most sustainable and natural of materials, having a generally positive effect in particular on the carbon dioxide levels of the planet, as carbon dioxide is consumed by growing trees for timber supplies.

Housing the growing populations of the world is also an issue inextricably linked to the sustainability and carbon dioxide questions that concern planners and politicians.

Timber frame buildings answer many of these questions, being more affordable in construction, less time consuming, and using more sustainable and replaceable construction materials.

An increase in timber frame building appears likely and in fact in many areas of the world is already the norm, such as North America, where timber supplies have always been plentiful and conditions have long been favourable.

In addition to the benefits of cost, the speed of construction of timber frame houses further adds to their desirability. With timber frame construction once the foundations for the building are laid, the inside of the building can be assembled from pre-constructed pieces, meaning only the outer cladding or brickwork needs to be bespoke.

In parts of the world however have inherent problems with timber frame buildings. In particular in the UK the prevalence of damp conditions leads to problems with rising damp. The, frequently brick faced, timber framed buildings that are increasingly built in the UK are constructed on hard standing, frequently concrete foundations.

Due to the increasing use of timber and cost savings, fast growing varieties of trees are often used for construction timber. These fast growing varieties have a more open cell structure than the older more traditional hard woods used in similar applications in the past.

The timber that is used in today's economic climate adds to the problems created for the use of timber fame buildings because it is more susceptible to ingress of fluid than denser structured timber, and consequently more damp ingresses into the In damp conditions therefore the impermeable hard standing collects water, which correspondingly seeps through or is sucked up into the timber frame.

It is frequently predicted that in a number of years from now such buildings will have accumulated great problems as the timber frame rots.

Problems include: rotting of wood, corrosion of metallic fixtures, deterioration of electric installations; deterioration of floor coverings and furniture; damp spots on the floors and walls; plaster deterioration; bleaching and blistering of paint; effloresce; health dangers for occupants; and reduces the life of structures

Prior Art

Damp in constructions may be prevented by a number of means such as integrating damp prevention methods such as: treating the constructions elements post construction, i.e. drill holes into the wall at regular intervals and inject a penetrating liquid (e.g. silicone) into the holes to form an integral seal in the element; surface treatment such as use of a damp blocking paint; or provision of a traditional damp proof course.

Each of the above acts by providing a barrier to the damp or moisture, either in the case of paint, to prevent the damp exiting the element, or in the case of silicone, to prevent damp passing from one part of the construction element to another.

Chief amongst the available damp proof systems in use today is the use of a damp proof course or similar.

Damp-proof courses have been used since ancient times. The Romans used a horizontal course of slate inserted in a wall to act as an impervious barrier. Building standards in many countries require most new buildings to incorporate a damp-proof course (horizontal barrier in a wall designed to prevent moisture rising through the structure by capillary action, often abbreviated to DPC) I (damp-proof membrane (DPM) performs a similar function for a solid floor) at the time of construction. This may consist of a thin strip of plastic, a course of engineering brick or slate, or a layer of bitumen.

A DPC is usually a thick plastic strip bedded into the mortar between two courses of bricks or blocks. It can often be seen as a thin plastic line in the mortar near ground level.

A DPM is usually a thick polythene sheet laid under the floor slab, to allow the slab to dry out and keep out groundwater. It is often laid on a bed of sand, to prevent the sharp edges of the hardcore damaging it. Variations of DPMs may be epoxy damp-proof membrane -an epoxy resin for suppressing residual rising damp in concrete which is applied by brush or roller in one or two coats; Polypropylene membrane -sheet membrane fixed with clips and tape; and bitumen-latex emulsion -a waterproofing compound, vapour barrier, damp proof membrane and protective coating applied by brush or roller.

However DPC and DPM when as common in sheet form, is frequently provided in a roll, cut to size at site and typically formed from plastics or bitumen.

Although such an impermeable layer is of great use in preventing highly damaging transference of moisture and is simple to use, it necessarily prevents moisture moving in either direction. Whereas moisture movement from the hard standing into the timber is undesirable, when the timber is holding water, such as for instance in the event of flooding, the moisture needs a route of egress from the timber. A traditional damp proof course will prevent this egress, holding the moisture in at the bottom of the timber frame.

In this sense a traditional damp proof course magnifies the problem and frequently the only means to remove flood water and the other ingressed damp from timber framing of a building is to strip back the interior plaster skim and plaster boarding to allow the timber to breathe and remove the moisture. This is a costly exercise.

There are ways of spacing timber from hard standing which alleviate or remove the problem outlined above. In smaller applications than house building the provision of spacers between the timber and hard standing -such as screws into the base of the timber -which allow air to circulate in the space provided by standing the timber off the hard standing.

This prevents liquid pooling and ingressing the timber. However it is impractical for any amount of timber other than in small applications due to the need to seat securely and evenly. Consequently another method must be used to separate timber from hard standing with greater regularity, increasing costs.

In addition in recent years the long standing recognition of ventilation requirements regarding buildings has been made more stringent. For instance in the UK the building regulations standards stipulate a certain number of air changes per hour and in addition buildings are pressure tested. Heat exchange systems are accordingly being used in construction with often electronic means to recover heat used in commercial applications and frequently domestic settings also.

An object of the present invention therefore is to provide a simple and effective means to prevent ingress of moisture into timber from hard standing and simultaneously allow moisture to egress from the timber.

Another object of the present invention is to provide a reliable and cost effective means to allow ventilation through the internal structure of a building.

A further object is to make such a means to meet the above two objects in a format that is of minimal cost, easy to use and largely analogous with existing materials and construction methods, in order to minimise disruption and facilitate widespread use.

Summasy of the Invention According to a first aspect of the invention there is provided a damp proof layer, adapted to be inserted between construction elements; said layer having a continuous surface with raised and lowered portions.

Preferably the construction elements contain timber and hard standing. The layer is disposed in use to provide separation between the timber and hard standing in a damp proof system.

Ideally the layer provides an impermeable central core. This prevents moisture passing from one element to another.

Ideally this layer is formed of plastic material which is in an extruded form.

In the preferred embodiment as well as the core providing a block to the passage of moisture the separation provides enough space for ventilation between the elements.

Ideally in order to provide separation between the elements the surface is crenellated, ridged, dimpled, or otherwise provided with raised portions standing away from the central core of the layer. The raised portions are the contact surface for the elements.

In the preferred embodiment the profile is triangular. This provides a strong shape less susceptible to any settling or deforming under the pressure or mass of the construction. In addition it provides a profile that provides regularity of decreased\su,-face area at the areas in contact with the elements and increased or complete surface area at the core.

In the preferred embodiment the layer has a triangular cross sectional profile in all directions, the raised portions being conical, or ideally pyramids having four sides.

In addition in the preferred embodiment these pyramids have fillets interconnecting the pyramids at the level of the core and have flattened tops at the level of contact with construction elements.

The fillets provide easy means to slice or cut the layer into the shapes required, providing a grid pattern for such a purpose.

Brief Descjjption of the Fiqpres Figure 1 shows a partial isometric overhead view of the preferred embodiment of the layer in a strip form.

Figure 2 shows an exploded view of the layer in use in a damp proofing system.

Figures 3 show various configurations in profile of the surface of the layer.

Detailed Description of the Figures

The preferred embodiment of the layer (1) shown in Figure 1 has raised portions (10) with triangular profiles on four sides (11), and may be described as pyramids with the bases (12) at the core (13) and the flattened apexes (14) forming a surface, said surface contacting in use with the construction elements (not shown in this Figure).

The flattened tops (14) prevent the pyramid apexes cutting into or having any tendency to sink into construction elements such as timber, which would in turn lead to unpredictable seating of such elements.

In addition regular mechanically flattened apexes provide a regular contact surface on the layer for an element of any nature, mitigating against the elements being seated incorrectly from the likelihood of wear affecting the surface level by flattening apexes randomly.

The pyramids whose apexes (14) thus form the surface have bases at the core that are spaced from each other by a mesh or grid of largely equidistant spacing (15).

This promotes a facility in segmenting of the layer for simple resizing on site, such as by slicing with a box cutter through the grid of spacing (15).

Typically the pyramids forming the surface range from between 0.5 to 1 cm from base (the core of the layer) to apex (the surface in contact with an element). The grid of the core between the pyramids typically will have a thickness of a few millimetres and the spacing between the pyramid bases will be approximately a few millimetres also.

The grid of spacing 13 between the pyramid bases 12 in addition is disposed to divert and absorb any deforming pressure on the pyramids 10.

The space between the pyramids 10 is additionally capable of allowing ventilation, as air is able to pass in at least two perpendicular directions, i.e. along the line of the The other side of the layer 10 is disposed in largely the same manner, with the Figure showing a foreshortened view. In this manner the elements (not shown in this Figure) may be separated one from the other and furthermore from the impermeable core 12. This allows for run off of moisture and furthermore ventilation as the grid spacing 13 will in use provide ventilation from one side of the element to the other(s).

Figure 2 shows the use of the layer in a damp proofing system in a timber frame construction. The layer I is inserted between the base plate 21 of the timber frame 2, and the foundation or brick course 3.

Figures 3 show three different configurations for the surface of the layer with the raised portions and the lowered portions being formed by varied shapes.

It is conceivable that any or all of these shapes or others may be preferred, with variation being dependent on materials, use, cost and/or preference.

With respect to the above description then, it is to be realised that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.

Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Claims (13)

1. CLAIMS1. A damp proof layer, adapted to be inserted between construction elements; said layer having a continuous surface with raised and lowered portions.
2. 2. A damp proof layer according to claim I where the construction elements comprise timber and hard standing.
3. 3. A damp proof layer according to claims I or 2 in the form of a strip.
4. 4. A damp proof layer according to claims 1, 2 or 3, having a first surface that is flat and a second surface that is corrugated.
5. 5. A damp proof layer according to any preceding claim, has a first surface that is flat and a second surface that has raised indentations.
6. 6. A damp proof layer according to any preceding claim, wherein the raised indentations have a triangular profile in one direction.
7. 7. A damp proof layer according to claim 6, wherein the raised indentations have a triangular profile in a second direction which is orthogonal to the first, forming pyramids.
8. 8. A damp proof layer according to claim 7 where the pyramids have flattened apexes.
9. 9. A damp proof layer according to any preceding claim includes holes.
10. 10. A damp proof layer, wherein the material is in a roll.
11. 11. A damp proof layer according to any preceding claim wherein the layer includes or is formed from plastics.
12. 12. A damp proof layer according to any preceding claim wherein the layer includes or is formed from polyurethane.
13. I 3. Method of fabrication for a damp proof layer according to any preceding claim includes rolling.