GB2189833A - A method of restoring a wooden structural member - Google Patents

Description

GB2189833A 1 SPECIFICATION that is sealed into the recess. This would re

sult in the statically undesirable situation of a A method of restoring a wooden structural fixed beam, apart from the fact that it is un member known whether the open joints continue and 70 at what location such an open joint termi This invention relates to a method of restoring nates, which may lead to unwelcome surprises a wooden structural member whose bearing when injecting the plastic.

capacity is no longer adequate due to decay It is an object of the present invention to or other cause, said method comprising mak- improve a restoration method of the above ing at least one cut-out extending from non- 75 described type in such a manner that the deteriorated wood as far as a support, such above drawbacks are eliminated.

as a wall support, or non-deteriorated wood This is achieved according to the present of a further structural member, providing a re- invention by injecting at least the voids pro inforcement in said cut-out and subsequently duced by rot orotherwise entirely with a foam filling said cut-out with a liquid plastic mastic 80 ing plastic before making the cut-out in the functioning, after hardening, as a mechanical form of an open slot extending partly through joint between the wooden structural member the plastic foam. These steps allow to fill the and the support. entire void and any offshoots thereof with A similar restoration method is known from relatively inexpensive plastic foam. The subse- Dutch patent specification 148,675, and is 85 quent cut-out made in the form of a slot thus destined in particular for restoring beams, one has dimensions that can be accurately deter end of which supported in a wall is affected mined, so that also the quantity of plastic by rot or otherwise. The cut-out to be made mastic to be subsequently injected can be ac consists of an elongate drilled hole connecting curately determined and optimized. Said plastic the void produced by the rotted beam end to 90 foam thus functions not only as a relatively the atmosphere. The drilled hole extends from inexpensive filler for the void but at the same the void through the adjoining mouldered and time as a permanent formwork for the plastic affected wood and along a substantial path mastic to be injected subsequently, so that through sound wood. The reinforcement is in- the quantity thereof to be used can be opti troduced from the mouth of the drilled hole 95 mally minimized, depending on the loads to be from the outside and extends substantially the taken up, while moreover the restoration can entire length of the drilled hole into the void, be realized with minimal operations and in par after which the liquid plastic mastic is injected ticular with no demolition and restoration op via said mouth until the entire void and the erations.

drilled hole are filled up. 100 Besides, this restoration method is also suit The manner in wich the drilled hole is made able for rehabilitating timber joints, i.e. two implies an inclined direction thereof relative to abutting and coupled wooden structural mem the longitudinal direction of the beam to be bers. An affected joint can be restored effec restored and hence also a reinforcement in- tively by a plastic plate whose outer circum- stalled in inclined fashion. This has the 105 ference is partly defined by means of a foam drawback that the load to be taken up by this mould.

inclined reinforcement exerts a buckling force, Moreover the method according to the pre resulting in fracture. Furthermore, the bending sent invention also has a more general field of forces, as a result of the inclined reinforce application, i.e. the method allows to realize ment, have been found to entpil the risk of 110 also objects and effects other than those cleavage of the beam. achieved with the above described known It has also been found in practice that method. For instance, the method according mostly a formwork has to be installed, which to the present invention can also be employed has to be removed later on. In particular with for restoring e.g. a broken beam, with any wall-supported beams, this leads to labour-in- 115 voids produced as a result of broken-off tensive and expensive operations on account pieces or removed splintered timber being of the required removal of brickwork around filled up with plastic foam.

the recess. The formwork may not be re- For restoring a wooden beam according to moved until the liquid plastic introduced has a further preferred embodiment of the present hardened, which mostly takes a day, after 120 invention, the slot is made in vertical direction which the removed brickwork has to be rein- of the beam and extends to adjacent the bot stated. A further drawback of this method is tom face of the beam, e.g. a slot extending to the consumption of appreciable quantities of about 2 cm from the bottom face of the relatively expensive plastic material. This ap- beam. At the support in the wall, the slot is plies the more so as the brickwork in the wall 125 made in such a manner that the plastic plate may be irregular and mostly contains partly to be formed can find support on the special open joints. The liquid plastic will penetrate face in the recess.

also into these additional spaces, thereby fur- The entire wooden structural member can ther increasing the consumption and, more- be reinforced when according to a still further over, entailing the risk that a beam is obtained 130 embodiment of the present invention, the slot 2 GB 2 189 833A 2 is made along the full length of the wooden and transmission of loads, so that the bearing structural member. In this manner, the original capacity of beam 1 is appreciably reduced.

wooden structural member, e.g. a wooden For restoring the bearing capacity of beam beam, provided with decorations, in the form 1, the cavity produced by the decayed beam of wood carving or paintings, can be presend and the ever present cavity between the erved in spite of the lost bearing function due original beam end 4 and recess 2, as well as to rot or otherwise, which is highly advan- its offshoots, e.g. joints remained partly open, tageous especially in the restoration building is filled up with a foaming plastic 7, e.g. poly industry, among other things on account of urethane foam. The injection can be realized in the constancy of the original circumferential di- 75 different manners. In case beam 1 has decay mensions of the wooden structural member. areas extending to beyond the wall face, the The anchoring of the plastic plate in the injection can be done via said areas. When sound wood can be improved in accordance such a place is not available, the cavity can with a further embodiment of the present in- be made accessible by providing an access in vention when in vertical and/or longitudinal di- 80 beam 1 or wall 3.

rection of the slot, at least one groove is It is observed that in the embodiment made in the sound wood, the circumferential shown, the affected area 6 of beam 1 has surface of each groove extending to beyond been left unperturbed in actual fact. Naturally, the circumferential surface of the slot. As a it is also possible to remove the affected result the plastic plate to be formed is pro- 85 wood prior to injecting the foam 7. It is even vided with laterally extending ridges which possible to saw off the beam end in the unaf eliminate the risk of detachment of the plastic fected wood, e.g. just outside the wall face.

plate relatively to the sound wood. Ridges in After filling. the cavities with the foaming vertical direction can be realized in a very sim- plastic 7, a slot 8 is provided centrally in, and ple manner when in accordance with a pre- 90 in vertical direction of, beam 1, extending ferred embodiment of the present invention, from the unaffected wood to about the plane the groove consists of a part of the circumfer- containing the original end 4 of beam 1. Slot ential surface of a bore. When in accordance 8 thus extends, accurately defined, from the with a further embodiment of the present in- sound wood through any affected wood into vention, each bore has a diameter larger than 95 the plastic foam 7. Slot 8 is made from the the width of the slot and has a centre axis top of beam 1 e.g. by means of a chain saw lying in the median perpendicular plane of the or cutter. The slot extends to adjacent the slot, the bores can advantageously serve as bottom face of beam 1. For instance, a slot is guides for providing the slot. This can be ef- conceivable having a width of approximately 4 fected in a simple manner when the slot is 100 cm, extending to about 2 cm above the bot made by means of a chain saw or cutter. tom face of beam 1. Within the recess 2, slot Some embodiments of the restoration 8 is countersunk in such a manner that the method according to the present invention will bottom face of the slot has a force-transmitt now be described, by way of example, with ing function, i.e. the bottom face is formed by reference to the accompanying drawings, in 105 the bearing surface of recess 2 and possibly which: by unaffected wood of beam 1.

Fig. 1 is a cross-sectional view of a beam Provided in vertical direction of slot 8 is a end restored according to the present inven- bore whose centre line lies in the median per tion and supported in a wall; pendicular plane of slot 8 and whose diameter Fig. 2 is a cross section on the line 11-11 of 110 is larger than the width of the slot. The bore Fig. 1; can be provided either before or after slot 8 Fig. 3 is a lateral view of a diagrammatically is made. When this is done before, the bore shown joint between two wooden structural may serve as a guide means for the provision members restored in accordance with the pre- of slot 8. After said slot has been made, the sent invention; 115 bore, relatively to the slot, results in two Fig. 4 is a cross section on the line IV-1V of grooves 9 extending into the sound wood.

Fig. 3; and In slot 8 is installed a reinforcing rod 10 Fig. 5 shows a variant of the restored joint made of e.g. glass fibre, steel, synthetic plas shown in Fig.3. tics fibres and the like. Naturally, it is also Figs. 1 and 2 show the right end of a woo- 120 possible to install more reinforcing rods or no den beam 1, which end is supported in a rod at all.

recess whose contour line is indicated at 2, in Finally, slot 8 is filled with a liquid plastic a wall 3. The original contour of beam 1 mastic, e.g. an epoxy resin, whether or not within the recess is indicated in dashed line 4. mixed with suitable materials, such as sand, However, the end has been affected by rot 125 gravel, pigments and the like. After hardening, and reduced to line 5. As far as this line, the there is thus formed a reinforcing plate 11 beam end has been decayed entirely. The rehaving such mechanical properties that the maining beam end is affected in the area indi- bearing capacity of beam 1 is completely re cated at 6, which implies that area 6 can stored again. Although there is normally a su hardly, if at all, contribute to the taking up 130 fficient bond between the sound wood and 3 GB2189833A 3 plate 11 to ensure the desired anchoring of cuts 32, 33 through wood not yet affected.

plate 11 in beam 1, said anchoring is addition- The resulting space, whether or not after en ally promoted by synthetic plastics material casing, is filled by injecting a foaming plastic hardened and penetrated into grooves 9, 26, after which, as described hereinbefore, a thereby providing the plate with ridges integral 70 reinforced or non- reinforced plate 31 is therewith. formed.

It is observed that more than one bore can The restoration method is not only suitable be provided to produce a corresponding addi- for restoring decayed wooden structural mem tional number of ridges. It is also possible, bers and joints, but, as shown e.g. in Fig. 5, after the provision of slot 8, to provide in its 75 also a broken beam can be restored in this side walls grooves extending longitudinally of manner. According to the method shown in said slot, e.g. grooves extending perpendicular Fig. 5, the splintered and worn-out fracture to the bore, thereby producing a plate having faces are removed by sawing. Naturally, it is on its sides a network of projecting ridges. also possible to refrain from sawing away por Such a solution can be sought when only little 80 tions, thus obtaining a situation comparable to space is availabe in the sound wood, so that that shown in Figs. 3, 4.

only a relatively short slot can be made. On A fractured beam will mostly be caused by the other hand, it is also possible to extend an excessive load. The mere restoration of the slot 8. For instance, as shown in chain-dotted beam will hardly be useful when it has again lines 12 in Figs. 1 and 2, the slot could ex 85 to be subjected to the same load. In that tend the full beam length, e.g. from the one case, the present invention can be used to recess into the other, thus resulting in a beam advantage, for it also enables reinforcing the reinforced throughout. This solution can be beam. As mentioned in the discussion of Figs.

chosen when e.g. the original joist frame in a 1, 2, this can be realized by extending the historic building is to be preserved, in spite of 90 slot and hence the plate to be formed. This is a functional change of the building, so that the shown in Fig. 5 in chain- dotted lines 34, 35.

joist frame should have a greater bearing The-extension of the plate can be effected capacity than was originally anticipated. along any desired path up to including the Figs. 3 and 4 show a beam 20 jointed to a total beam length. Also the extended plate beam 21 in a manner not shown. The joint 95 can be provided with the desired reinforce not shown may be any joint form between ment and can be fitted with lateral ridges in two wooden structural members. At the joint, vertical and longitudinal direction of the plate the beam ends are decayed as far as lines 22, so as to increase the anchoring effect.

23, while the areas 24, 25 adjoining the re- It stands to reason that many modifications maining beam ends are affected. In accor- 100 and variants are possible within the scope of dance with the present invention, the spaces the present invention relatively to the above produced by decay are filled up with a foam- described embodiments shown in the draw ing plastic 26. In order to maintain the con- ings. A number thereof have already been dis tour line of the joint, prior to the injection of cussed above. It is moreover observed that the foaming plastic 26, there is provided an 105 the formation of more than one plate in a encasing, which is subsequently removed beam is also possible, depending upon the again. However, this is not necessary, as the load and the beam dimensions. Besides, plastic foam can be easily processed, so that grooves provided in vertical direction of the the desired contour can be provided after- slot are always made by providing bores wards in a simple manner. 110 which are moreover made symmetrical relative Subsequently, a slot 27 is made to extend to the slot. Naturally, differently formed and/or from the unaffected wood of beam 20 into asymmetrically placed grooves can be pro the unaffected wood of beam 21. At its ends, vided, while the number thereof may vary per slot 27 terminates in a bore, thereby produc- plate to be formed, which also applies to the ing an enlarged and rounded slot end wall 28, 115 longitudinal grooves.

29.

Claims (8)

1. In slot 27 is installed a reinforcing rod 30, CLAIMS after which slot 27

   is filled with a liquid plas- 1. A method of restoring a wooden structu tic mastic forming, after hardening, a connect- ral member whose bearing capacity is no lon ing plate 31, having at its ends thickened, 120 ger adequate due to decay or other cause, rounded ridges, so that the load bearing and comprising providing at least one cut-out ex transmitting properties of the joint are again tending from unaffected wood as far as a entirely restored. support, such as a wall support, or unaffected In the above described restoration method, wood of a further structural member, provid the affected beam ends 24, 25 have remained 125 ing a reinforcement in said cut-out and subse unperturbed, in actual fact. Naturally, it is also quently filling up said cut-out with a liquid possible to remove the affected wood before plastic mastic functioning, after hardening, as injecting the foaming plastic 26, even using a mechanical joint between the wooden struc the step shown in Fig. 5, wherein the beams tural member and the support, characterized 20, 21 have been shortened by means of saw130 by injecting at least the spaces produced by 4 GB2189833A 4 decay or other cause entirely with a foaming plastic before providing the cut-out in the form of an open slot extending partly through the foam plastics.
2. 2. A method as claimed in claim 1, wherein the wooden structural member to be restored consists of a wooden beam, characterized in that the slot is provided in vertical direction of the beam and extends to adjacent the bottom face of the beam.
3. 3. A method as claimed in claim 1 or 2, characterized in that the slot is provided along the entire Length of the wooden structural member.
4. 4. A method as claimed in any one of the preceding claims, characterized in that there is provided in vertical and/or longitudinal direction of the slot at least one groove in the unaffected wood, the circumferential surface of each groove extending to beyond the circumferential surface of the slot.
5. 5. A method as claimed in claim 4, characterized in that the groove consists of a part of the circumferential surface of a bore.
6. 6. A method as claimed in claim 5, characterized in that each bore has a diameter larger than the width of the slot and has a centre line lying in the median perpendicular plane of the slot.
7. 7. A method as claimed in any one of the preceding claims, characterized in that the slot is provided by means of a chain saw or cutter.
8. 8. A method of restoring a wooden structu- ral member substantially as hereinbefore described with reference to the accompanying drawings.

   Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987. Published at The Patent Office, 25 Southampton Buildings, London. WC2A 1 AY, from which copies may be obtained.