GB2146376A - Door frames - Google Patents

Abstract

A fire-check door arrangement comprises a door frame having a door butt or stop made of a fire-retardant material such as cement wood chip particle board, the remainder of the frame being of hardwood or softwood.

Description

SPECIFICATION Improvements in Fire Check Door Arrangements This invention relates to a fire-check door arrangement.

Our U.K Patent Application No.8315090 describes a block board door which has a softwood outer frame, a softwood solid core consisting of battens extending across the width of the door, and a sheet facing bonded to the frame and core on both sides of the door. Due to the use of horizontal instead of vertical battens, improved fire-check properties can be obtained. Alternatively, existing fire-check standards can be met with a thinner door.

A difficulty which can arise, however, especially with a thinner door, is that of checking flames which tend to creep around the edge of the door where it is closed against the frame of the door opening. In accordance with conventional practice, this problem can be reduced or overcome by using a frame for the door opening which has an intumescent strip incorporated therein. This, however, means that the frame of the door opening is expensive both to manufacture in the first place and to install in place of an existing softwood frame for the door opening.

We have now found that, with the block board door of our Application No. 8315090, fire-check standards can be met in a different way.

According to the present invention there is provided a fire-check door arrangement which comprises the combination of a fire-retardant door with a frame for the door opening wherein only the door butt is made of a fire-resistant material, such for example as cement wood chip particle board.

The fire-retardant door is preferably the door subject of our U.K. Patent Application No. 8315090.

By use of the fire-retardant door stop or door butt of this invention, improved resistance or check against spread of fire is achieved. The improvement effected is at least 50%. Thus, in the case of a 38 mm door blank closed into a door frame having a hardwood or softwood door butt, where under a given fire test the fire was checked for about 20 minutes, the combination of this invention, using a thinner door blank 35 mm thick, was able to check fire in a corresponding test for at least 30 minutes.

The accompanying drawing illustrates a door frame in accordance with the invention.

Reference 10 generally denotes the frame, and reference 12 denotes the door butt or door stop against which the door abuts when closed. The door (not shown) is a door as described and illustrated in ourcopending Application No.8315090.

The door frame is made of hardwood or softwood except for the door butt 12, which is made of cement wood chip particle board, although any similar fire-retardant material could be employed.

Advantageously, when a fire-retardant door is installed, it is necessary only to produce a frame for the door opening in which the usual wood door butt is replaced by a fire-retardant door stop, and this is clearly especially beneficial when an existing frame for a door opening is being modified to receive a fire-check door.

1. A fire-check door arrangement which comprises the combination of a fire-retardant door with a frame for the door opening wherein only the door butt is made of a fire-resistant material.

2. An arrangement according to claim 1, wherein the door is a block board door having a solid core comprising softwood battens extending across the width of the door.

3. An arrangement according to claim 1 or claim 2, wherein the fire-resistant material is cement wood chip particle board.

4. An arrangement according to claim 1 or claim 2 or claim 3 wherein, except for the door butt, the door frame is made of hardwood or softwood.

5. A fire-check door arrangement substantially as hereinbefore described with reference to the accompanying drawings.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1,2,3,4 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows: (c) Claim 5 above has been re-numbered as 4 and their appendancies corrected.

1. A fire check door arrangement comprising a fire retardant door mounted in a door frame provided with a door butt, the door being made of block board having a solid core comprising softwood battens extending across the width of the door, and wherein for the frame only the door butt is made of fire resistant material.

2. An arrangement according to claim 1 or claim 2, wherein the fire resistant material for the butt is cement wood chip particle board.

3. An arrangement according to claim 1 or claim 2 or claim 3 wherein, except for the door butt, the door frame is made of hardwood or softwood.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in Fire Check Door Arrangements This invention relates to a fire-check door arrangement. Our U.K Patent Application No.8315090 describes a block board door which has a softwood outer frame, a softwood solid core consisting of battens extending across the width of the door, and a sheet facing bonded to the frame and core on both sides of the door. Due to the use of horizontal instead of vertical battens, improved fire-check properties can be obtained. Alternatively, existing fire-check standards can be met with a thinner door. A difficulty which can arise, however, especially with a thinner door, is that of checking flames which tend to creep around the edge of the door where it is closed against the frame of the door opening. In accordance with conventional practice, this problem can be reduced or overcome by using a frame for the door opening which has an intumescent strip incorporated therein. This, however, means that the frame of the door opening is expensive both to manufacture in the first place and to install in place of an existing softwood frame for the door opening. We have now found that, with the block board door of our Application No. 8315090, fire-check standards can be met in a different way. According to the present invention there is provided a fire-check door arrangement which comprises the combination of a fire-retardant door with a frame for the door opening wherein only the door butt is made of a fire-resistant material, such for example as cement wood chip particle board. The fire-retardant door is preferably the door subject of our U.K. Patent Application No. 8315090. By use of the fire-retardant door stop or door butt of this invention, improved resistance or check against spread of fire is achieved. The improvement effected is at least 50%. Thus, in the case of a 38 mm door blank closed into a door frame having a hardwood or softwood door butt, where under a given fire test the fire was checked for about 20 minutes, the combination of this invention, using a thinner door blank 35 mm thick, was able to check fire in a corresponding test for at least 30 minutes. The accompanying drawing illustrates a door frame in accordance with the invention. Reference 10 generally denotes the frame, and reference 12 denotes the door butt or door stop against which the door abuts when closed. The door (not shown) is a door as described and illustrated in ourcopending Application No.8315090. The door frame is made of hardwood or softwood except for the door butt 12, which is made of cement wood chip particle board, although any similar fire-retardant material could be employed. Advantageously, when a fire-retardant door is installed, it is necessary only to produce a frame for the door opening in which the usual wood door butt is replaced by a fire-retardant door stop, and this is clearly especially beneficial when an existing frame for a door opening is being modified to receive a fire-check door. CLAIMS

1. A fire-check door arrangement which comprises the combination of a fire-retardant door with a frame for the door opening wherein only the door butt is made of a fire-resistant material.

2. An arrangement according to claim 1, wherein the door is a block board door having a solid core comprising softwood battens extending across the width of the door.

3. An arrangement according to claim 1 or claim 2 or claim 3 wherein, except for the door butt, the door frame is made of hardwood or softwood.

3. An arrangement according to claim 1 or claim 2, wherein the fire-resistant material is cement wood chip particle board.

4. An arrangement according to claim 1 or claim 2 or claim 3 wherein, except for the door butt, the door frame is made of hardwood or softwood.

5. A fire-check door arrangement substantially as hereinbefore described with reference to the accompanying drawings.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1,2,3,4 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows: (c) Claim 5 above has been re-numbered as 4 and their appendancies corrected.

1. A fire check door arrangement comprising a fire retardant door mounted in a door frame provided with a door butt, the door being made of block board having a solid core comprising softwood battens extending across the width of the door, and wherein for the frame only the door butt is made of fire resistant material.

2. An arrangement according to claim 1 or claim 2, wherein the fire resistant material for the butt is cement wood chip particle board.