GB2483670A

GB2483670A - A method of sealing a joist end in a masonry wall

Info

Publication number: GB2483670A
Application number: GB1015406.0A
Authority: GB
Inventors: Andrew Rollo
Original assignee: Intelligent Wood Systems Ltd
Current assignee: Intelligent Wood Systems Ltd
Priority date: 2010-09-15
Filing date: 2010-09-15
Publication date: 2012-03-21
Also published as: GB201015406D0

Abstract

The method comprises providing a masonry wall 12 including at least one joist 20, which has an end portion embedded in a hole 32 through the wall; locating a planar member 34 over the hole and bonding the planar member to the outer surface of the wall 26 which, in use, provides an airtight seal. The planar member may be a strip of tape bigger than the hole and it may have an adhesive surface which may secure the member to the wall providing a watertight seal. An end cap may be applied to the end of the joist prior to embedding in the wall to provide further protection. The joist may be solid timber or an I-joist and the joist may be treated to prevent shrinkage. A building system comprising this planar member to seal the hole in the masonry is also claimed.

Description

METHOD AND ASSEMBLY FOR

SEALING A JOIST END IN A MASONRY WALL

The present invention relates to building construction and in particular, though not exclusively, to a method and assembly for sealing a joist end in a blockwork or brickwork wall.

One traditional method of building construction locates joists in the supporting walls. A course of blocks or bricks are laid to a desired level. Joists are then laid across the brickwork to provide the support for floors and/or ceilings. The joists are preferably positioned on the brickwork so that their ends are located in the wall and thus are fully supported by the wall. Bricks are laid around and over the joist ends to complete the wall. Figure 1 illustrates a typical arrangement where the joist A extends through the wall B, the joist being supported by the lower course of brickwork C. This provides an inner wall B. An external wall D is then constructed across a void E, providing a cavity wall, to improve thermal and acoustic insulation.

While mortar F is located around the joist to provide a seal when constructed, the seal can be breached as the mortar settles on drying and the timber shrinks and possibly splits with age. When the seal is lost, gaps are created through the wall B which provide leakage paths and conseguently reduce the fire-retardant, thermal and acoustic performance of the wall.

The problem is exacerbated for I joists as compared to solid timber, due to the additional space which exists on either side of the central web. This space must be filled up with mortar which tends to slump downwards and shrink during drying. As a result joist end caps have been developed for I joists. These are designed to fill-in the space and create an end to the joist which has a rectangular profile similar to a solid timber joist.

Simple blocks of wood have been added, which are held by silicone sealants. These are typically performed as on-site construction which is laborious and could result in gaps being left through the sealant. Specially constructed end caps, such as those described in GB 2406343 to Boise Building Products Ltd, provide an end plate to the I joist, with extending portions to locate in the spaces and hold onto the joist. This end cap increases the overall length of the joist and the fit' requires to be good, in order to maintain the seal. The Stopper, as provided by Cullen Building Products Ltd, is a two part construction, locating on either side of the I joist and providing a flexible material to fill the space.

While such arrangements, improve the seal at the spaces in an I joist, they still provide a substantially rectangular end which requires to be sealed into the masonry wall using mortar. Thus, they have the disadvantages experienced in the solid timber joist arrangement and additionally are expensive and laborious to install.

GB 2420800 to Vaughan and Hennen, describes a cap for a joist in a blockwork wall. The cap comprises an end plate arranged to cover the end of the joist and substantially to seal the hole through the blockwork of the wall. The end plate has an upper edge portion and/or a lower edge portion lying generally in the plane of the end plate and arranged to overlap an outer face of the blockwork wall above/below the hole. The Safety Fast Joint Cap, as provided by Simpson Strong-Tie Limited, uses a similar principle, but entirely encases the joist end in a cap and provides edge portions which overlap the inner face of the masonry wall. These are formed from a plastics material such as uPVC, to give a degree of flexibility in fitting. However such a material can be damaged easily during construction; where the joist does not fit perfectly, wedges or steel plate restraints must also be fitted; and the caps are held and sealed in place using mortar. Conseguently, while an improved seal may be provided, these caps have disadvantages in cost, increased on-site construction time, and may still suffer from leakage when the mortar dries out.

As building standards increase there is a need for systems and materials to improve building performance in relation to acoustic, thermal and fire retardant properties without drastically altering the manufacturing operation or the construction process.

It is an object of the present invention to provide a method and system of sealing a joist end in a masonry wall which mitigates at least some of the disadvantages of the prior art described above.

According to a first aspect of the present invention, there is provided a method of sealing a joist in a masonry wall, the method comprising the steps: a) providing a masonry wall including at least one joist, the joist having an end portion embedded in a hole through the masonry wall; b) locating a substantially planar member over the hole on an outer surface of the wall; and o) bonding the planar member to the outer surface around the hole and thereby providing an airtight seal to the hole through the masonry wall.

By enclosing the hole from the outer surfaoe of the wall, opposite from the extending joist, any gaps which can appear around the joist within the masonry wall are negligible as a seal is maintained using the planar member. Thus the member is in addition to using standard mortar so there is no dependence on the mortar to provide the seal.

Preferably a first surface of the member is adhesive and thus the method may include the step of adhering a first surface of the member to the outer surface of the wall. Advantageously the adhesive provides the seal.

The planar member can therefore be in the form of a strip of tape, having a width greater than a width of the hole. A user simply removes sufficient length of the tape to cover the length of the hole. A suitable tape may be commercially available flashing tape.

Preferably the member provides a watertight seal in addition to an airtight seal. Currently available tape for cladding work may be used as it is a waterproof bituminous self-adhesive flashing tape that bonds securely to brickwork, concrete and cement. Such a tape is EVO-STIK® FLASFIBAND by Bostik Ltd. The method may include the step of coating an area of the outer surface of the wall around the hole with a primer.

Advantageously the primer improves adhesion of the member on porous, rough, dusty surfaces in cold or damp weather.

Such an arrangement can advantageously be applied by a relatively unskilled worker.

Alternatively the seal may be provided by a sealant located between the outer surface of the wall and the first surface of the member. The sealant may initially be applied to the wall or the member.

The member may be applied to the wall either while the mortar is drying or has dried. This allows for some visual inspection of the mortar seal prior to application of the member.

Alternatively an outer leaf can be constructed quickly if the member is applied to drying mortar.

The method may include the step of applying an end cap to the joist, prior to embedding the joist in the masonry wall. This will reduce the quantity of mortar used, particularly for I joists, and the member can adhere to an end plate of an end cap, if desired.

According to a second aspect of the present invention, there is provided a building system comprising; a masonry wall including at least one joist, the joist having an end portion embedded in a hole through the masonry wall; and a substantially planar member, the member extending over the hole on an outer surface of the wall and being bonded to the outer surface around the hole to thereby provide an airtight seal to the hole through the masonry wall.

The masonry wall may comprise courses of brickwork or blockwork as is known in the art. The joist is preferably a solid timber joist. More preferably the joist is a solid timber joist treated to prevent shrinkage. The joist may be treated with a water repellent. Additionally the joist may be treated with a fire retardant. Alternatively the joist may be an I joist as is known in the art. The joist may include an end cap as is known in the art.

Preferably the planar member is substantially rectangular.

Preferably also the member has a thickness of less than one millimetre. Alternatively, the thickness may be equal to or greater than one millimetre, but will not be greater than the typical void found in cavity walls.

Preferably a first surface of the member is adhesive and thus the member adheres to the outer surface of the wall, entirely surrounding the hole. Advantageously the adhesive provides the seal.

Preferably the member provides a watertight seal in addition to an airtight seal. Currently available tape for cladding work may be used as it is a waterproof bituminous self-adhesive flashing tape that bonds securely to brickwork, concrete and cement. Such a tape is EVO-STIK® FLASHBAND by Bostik Ltd. Alternatively the seal may be provided by a sealant located between the outer surface of the wall and the first surface of the membey.

The adhesive or sealant may be applied in a continuous unbroken pattern towards the perimeter of the member. In this way, the seal may be formed from a ring created around the hole on the outer surface.

The building system may include a plurality of joists embedded in a masonry wall, there being a member located on the outer surface of the wall sealing the hole at each location of a joist. Preferably also, a second masonry wall may be constructed adjacent the outer surface to provide a cavity wall. The members will thus be hidden from view as they will be located in the void between the leaf's of the cavity wall and will also not be exposed to the environment. Where a single masonry wall is constructed with embedded joists, the outer surface may be rendered to cover the members.

An embodiment of the present invention will now be described, by way of example only, with reference to Figures 2 and 3 of the following drawings of which: Figure 1 is a sectioned side view through a cavity wall

constructed according to the prior art;

Figure 2 is a sectioned side view through a cavity wall constructed according to the present invention; and Figure 3 is a schematic illustration a masonry wall constructed in accordance with the present invention.

Referring to Figures 2 and 3 of the drawings, there is illustrated a cavity wall, generally indicated by reference numeral 10, the wall 10 comprising an inner leaf 12 and an outer leaf 14. Each leaf 12, 14 is made up of courses of brick 16, or blocks, mortared together, as is known in the art. At required intervals a space is left in the line of bricks, the space being wide enough to fit an end 18 of a joist 20 between the bricks. The joist end 18 rests on a surface 22 of the bricks so that it is supported by the leaf 12. In the embodiment shown, the joist end 18 extends over the brickwork such that the end face 24 is planar with the outer surface 26 of the leaf. This location provides the maximum support, but if preferred the joist 20 can be located short of the surface 26.

The course is continued, providing bricks up the sides 28,30 of the joist 20. As the bricks are added the joist end 18 is mortared into the hole 32 formed in the wall 12 to accommodate the joist 20. Bricks are located over the joist end 20 which are also mortared to the joist end, thereby providing a seal between the wall 12 and joist 20 over the hole 32.

Further courses can be added, with joists located therein as desired for the location of floors and/or ceilings as the building requires.

On the outer surface 26 there is located a strip 34. Strip 34 is rectangular in shape and has a thickness of less than one millimetre. It is flexible, being formed of a waterproof bituminous material. The strip has a width greater than the width of the hole 32 and a length greater than the length of the hole 32. In this way it entirely surrounds the hole 32.

The strip 34 has a self adhesive applied to one side, the adhesive bonds to the stonework and mortar of the outer surface 26 around the hole 32. The bond provides a seal so that no air or water can leak from the outer surface 26 to an inner surface 36 of the wall 12, through the hole 32.

In a preferred embodiment the strip 34 is a self-adhesive flashing tape that bonds securely to brickwork, concrete and cement, being EVO-STIK® FLASHBAND by Bostik Ltd. Flashing tape is particularly suited to the task as it is available on a roll for easy dispensing; the adhesive forms an airtight seal; it is waterproof and fire retardant; it has a width greater than the typical width of a hole for embedding a joist; it is relatively cheap and readily available; and it requires no specialist handling or skill to apply.

Once the strip 34 is in place, the outer leaf 14 can be constructed for the cavity wall 10. The strip 34 is then hidden from view and not exposed to the elements. The strip 34 is also thin enough that it does not interfere with construction of the outer leaf 14. Alternatively, if a single wall 12 is constructed, other materials such as a render can be applied over the strip 34 without disturbing the seal.

The principle advantage of the present invention is that it provides a method and assembly for sealing a joist end in a masonry wall which gives a seal around the hole in the wall without relying on mortar or sealant located around the joist end.

The further advantage of the present invention is that it provides a method and assembly for sealing a joist end in a masonry wall which is simple and cost effective as it requires no specially designed caps' or other fixings to the joist.

A yet further advantage of the present invention is that it provides a method and assembly for sealing a joist end in a masonry wall which can be used with any type and size of joist embedded in an wall. Additionally, it is immaterial to the position of the joist end in the wall.

A still further advantage of the present invention is that it provides a method and assembly for sealing a joist end in a masonry wall which can use materials which are readily available and known to the building community.

It will be appreciated by these skilled in the art that modifications may be made to invention herein described without departing from the scope thereof. For example, while timber joists have been described, joists or beams of any material which can be embedded in a masonry wall can be used.

The dimensions of the member/strip can be changed to provide any suitable size to allow a hole of any smaller dimensions to be used. The hole can be of any shape. Any other sealant, mortar or bonding system can be used between the joist and masonry, indeed possibly for aesthetic reasons, the joist can float' on the masonry wall and all sealing is provided by the member.

Claims

CLAIMS1. A method of sealing a joist in a masonry wall, the method comprising the steps: a) providing a masonry wall including at least one joist, the joist having an end portion embedded in a hole through the masonry wall; b) locating a substantially planar member over the hole on an outer surface of the wall; and c) bonding the planar member to the outer surface around the hole and thereby providing an airtight seal to the hole through the masonry wall.
2. A method according to claim 1 wherein a first surface of the member is adhesive.r
3. A method according to claim 2 wherein the method include the step of adhering a first surface of the member to the outer surface of the wall.r
4. A method according to any preceding claim wherein the member is sealed to the outer surface.
5. A method according to claim 5 wherein the seal is also watertight.
6. A method according to any preceding claim wherein the member comprises a strip of tape having a width greater than a width of the hole.
7. A method according to any preceding claim wherein the method includes the step of coating an area of the outer surface of the wall around the hole with a primer.
8. A method according to any one of claims 4 to 7 wherein the method includes the step of locating a sealant between the outer surface of the wall and the first surface of the member. The sealant may initially be applied to the wall or the member.
9. A method according to any preceding claim wherein the member is applied to the wall while mortar in the hole is drying.
10. A method according to any preceding claim wherein the method includes the step of applying an end cap to the joist, prior to embedding the joist in the masonry wall.
11. A building system comprising; a masonry wall including at least one joist, the joist having an end portion embedded in a hole through the masonry wall; and a substantially planar member, the member extending over the hole on an outer surface of the wall and being bonded to the outer surface around the hole to thereby provide an airtight r seal to the hole through the masonry wall.
12. A building system according to claim 11 wherein the masonry wall comprises courses of brickwork or blockwcrk.
13. A building system according to claim 11 or claim 12 wherein the joist is a solid timber joist.
14. A building system according to claim 11 or claim 12 wherein the joist is an I joist.
15. A building system according to claim 13 or claim 14 wherein the joist treated to prevent shrinkage.
16. A building system according to any one of claims 13 to 15 wherein the joist is treated with a water repellent.
17. A building system according to any one of claims 13 to 16 wherein the joist is treated with a fire retardant.
18. A building system according to any one of claims 11 to 17 wherein the joist includes an end cap.
19. A building system according to any one of claims 11 to 18 wherein the planar member is substantially rectangular.
20. A building system according to any one of claims 11 to 19 wherein the member has a thickness of less than one millimetre.
21. A building system according to any one of claims 11 to 20 wherein a first surface of the member is adhesive to C) adhere to the outer surface of the wall.(\J
22. A building system according to any one of claims 11 to 21 wherein the planar member is a strip of tape, having a width greater than a width of the hole.
23. A building system according to any one of claims 11 to 22 wherein the seal is provided by a sealant located between the outer surface of the wall and the first surface of the member.
24. A building system according to any one of claims 11 to 23 wherein the system includes a plurality of joists embedded in a masonry wall, there being a member located on the outer surface of the wall sealing the hole at each location of a joist.
25. A building system according to any one of claims 11 to 24 wherein a second masonry wall is constructed adjacent the outer surface to provide a cavity wall. r C) r