4.1 General
4.1.1 Scope of Work
The scope of work includes the following:
Manufacture and installation of:
• Doors and door frames
• Counters and vanity units
• Fitted kitchen units (where required)
• Miscellaneous timberwork and specialist joinery All in accordance with drawings.
The doors should further comply with the specific sections of this specification.
4.1.2 Standards
Comply with the following standards where relevant and to the extent stated here.
• BS 5268 : 1991 Structural Use of Timber
• BS 1186 : 1988-91 “Timber for & Workmanship in Joinery”
• BS EN 942 : 1996 Timber in Joinery - General Classification of Timber Quality.
• BS 8000:1990, Part 5 Code of Practice for Carpentry, Joinery and General Fixings.
4.1.3 Setting out
All work is to be set out and constructed to the dimensions given and to the full intent of the drawings and specifications. Check dimensions on site before cutting or pre-fabricating components. In general, site dimensions will take precedence over drawings, the Engineer’s approval is however required in such cases.
4.1.4 Shop Drawings
Do not commence manufacture of joinery components without the prior approval of the Engineer and his agreement to the shop drawings. Details of construction shown on drawings prepared by the Engineer may only be altered with the prior agreement of the Engineer.
All work including joint types, fixings, etc must be detailed on shop drawings and approved by the Engineer before manufacture.
4.1.5 Samples
Prior to general manufacture, full size samples of each type of timber
construction must be fabricated and installed in order to approve all parts of the process.
4.1.6 Joinery in General
Unless otherwise specified, all joinery is to be purpose made, worked to detailed drawings where provided and constructed in accordance with approved best practice. It shall be mortised and tenoned, dowelled, dove-tailed, tongued, grooved, glued, pinned, screwed etc. as necessary and best suited for the particular purpose.
4.2 Materials
4.2.1 Timber Generally
All timber shall be sound, thoroughly seasoned, of mature growth, clean sawn, square-edged, free from sap, ring shakes, cracks, splits, large, loose or dead knots, boxed heart, wanly edges, insect attack, fungus growth, rot, dote or incipient decay, stained sapwood and other defects and shall be to the approval of the Engineer.
Timber shall be straight and true; any warped or twisted timers will be rejected.
All materials and components are to be stacked on suitable bearers clear of the ground and protected from the weather until they are fixed in position. If necessary provision shall be made for temporarily covering or otherwise protecting materials and components after they have been fixed in position 4.2.2 Hardwood for Internal Use
Unless otherwise specified, selected Beech (Fagns Sylvatica) or Cherry complying with the requirements of BS EN 942,Class J2 without sapwood.
Density to be approximately 700 kg/m3. 4.2.3 Hardwood for External use
Unless otherwise specified, selected Meranti Nimusu complying with the requirements of BS EN 942, Class J2 without Sapwood. Density to be approximately 700 kg/m3.
4.2.4 Exposed Timber
All faces of timber which will be exposed when the building is complete shall be wrought and shall have been selected as to quality of face. Grains shall be parallel to the length under max 60% degrees.
4.2.5 Pressure Impregnation
All Meranti timbers shall be vacuum treated for termite resistance and preservation.
Timber shall be impregnated by Hickson Vac-Vac process to achieve an average loading of 40 litres “Vascol WR” preservative per m3 of timber or equal.
All ‘cut ends’ joint forming, planning and/or any on-site cutting shall be liberally treated with Hickson “Vasele” end grain preservative.
4.2.6 Moisture Content of Timber
Timber shall be properly and carefully air seasoned to 20-25% moisture content prior to kiln drying. The moisture content shall be suitable for the situation of the finished timber but shall be limited to 11% ± 2% for internal use and 13%
± 2% for external work. When fixed in position the timber shall remain stable and free from any expansion or contraction or other movement which will detract from the satisfactory performance or required appearance of the
element. The timber shall be free from any drying defects whatsoever and there shall be no indication of shrinkage.
The Contractor shall replace at his own expense any timber which has been damaged or shrunk on finished work caused through the use of imperfectly seasoned timbers.
Immediately before manufacture the moisture content of timber should be ascertained using an electrical moisture meter to manufacturer’s
recommendations. Test 5% but not less than 10 lengths of each cross-section;
average results shall be in the centre of the specified range.
During delivery, storage, fixing and thereafter to practical completion maintain conditions of temperature and humidity suitable for specified moisture
content(s) of timber components.
The moisture content at the time of matching to the dimension indicated shall conform to the requirements of the said standard specification for the kiln drying of timber, for items customarily kiln dried. The timber in any
consignment shall be deemed to be satisfactorily kiln dried if upon inspection of representative samples drawing from the consignment, tests indicate that for:
Interior use/Interior joinery and door stock - At least 90% of the samples shall have a moisture content not exceeding 11% and the remaining samples shall have a moisture content not exceeding 13%.
Exterior joinery - At least 90% of the samples shall have a moisture content not exceeding 13% and the remaining samples shall have a moisture content not exceeding 15%.
The Engineer may require the Contractor to submit timber for testing. The Contractor shall replace joinery in which defects occur through improper moisture content.
4.2.7 Timber for Joinery
The Contractor shall carefully select the timber for joinery so to minimise disfiguring defects on finished faces.
4.2.8 Plywood
Plywood shall conform to the requirements of BS 1455:1972 grade 1 where varnished, grade 2 where painted, grade 3 where hidden. All plywood shall be obtained from an approved manufacturer. All plywood shall be resin bonded external quality. Both faces of all plywood shall have a fine sanded finish and be free from all knots except those which are sound and tight and exceeding 12mm diameter. Plywood shall, in addition to the general specification requirements for timber, be free from all defects such as lifting at the edges, blistering, surface cracks, sinking or raising of the surface due to defects in the base material and no patches or plugs will be permitted.
4.2.9 Fixings
Nails shall comply with BS 1202. Wood screws shall comply with BS 1210.
All other fixings shall comply with the requirements of the relevant British Standard or be of a good merchantable quality approved by the Engineer.
Any metal screws, bolts, nails, fastenings, fixing devices etc. used in the construction or fixing or joinery work to be located externally, shall be of stainless steel. All brad nails, etc. shall be best quality of appropriate gauge, strength and shall be long enough to enter the second timber for at least half their length before punched. Screws shall be of sufficient length and gauge for their purpose. Screws for door furniture and other ironmongery shall be of material and pattern to match the various fittings.
All screws for interior use shall be solid brass counter-sunk, flathead wood or twin fast screws. All nails and bolts for internal use shall be galvanised. All necessary fastenings and fixings are deemed to be included in the works even if not specifically mentioned in the drawings and specification.
All necessary means of support and connection are deemed to be included in the works even if not specifically mentioned in the drawings and specification.
4.2.10 Adhesives
Adhesives for external work shall be synthetic resins and comply with the requirements of BS 1204 : Part 2:1979 for the BR grade except that when glue lines are exposed to the weather they shall be of WBP grade.
Adhesives for internal work shall be synthetic resins complying with the requirements of BS 1204 : Part 2 and shall be MR or INT grade unless otherwise specified.
4.3 Execution
4.3.1 General
Timber for carpentry work shall be carefully sawn square and shall hold the full dimensions shown on the drawings. Softwood used in carpentry shall be put together with steel nails except where specified as framed when it shall be properly jointed and held together with glue and screws.
Timber, used for joinery work shall be finished wrot to the exact size shown on the drawings and no joinery shall be built in until inspected and approved by the Engineer. All work shall be carefully put together and properly jointed in accordance with best practice: all joints shall be glued and screwed or
dowelled. Any screws appearing on face work shall have the heads let in and be pelleted unless specified otherwise. All exposed rises in joinery work shall be pencil rounded.
All timber before being built-in shall be given specified coats of wood preservative or priming.
Joinery generally shall comply with the requirements of BS 1186: Part 1 for quality of workmanship and shall whatever possible be fabricated and assembled prior to delivery on site.
Joinery work is to be accurately set out framed and executed directly after the commencement of the building, but it is not to be wedged up until it is required for fixing in position. All exposed surfaces are to be wrot.
Except where the work is to be built-in obtain all dimensions for joinery works from the building structure. Carpentry work which does not form an essential part of the structural fabric shall not be carried out nor brought onto the building site until required.
Provide and maintain all temporary covering, and box in and protect all work liable to damage, and shall provide temporary doors where necessary during the progress of the work. Ensure that the work of other trades is properly arranged to obtain the best results both in the joinery and in other trades involved. Take all necessary measures to check or prevent capillary penetration of water in the joints and open connections of external joinery works.
4.3.2 Dimensions
Timber for joinery is to be wrote or moulded on all faces to the dimensions and shapes shown on the drawings or otherwise specified. Where nominal
dimensions are given a deduction of 4mm for each wrote or moulded face shall be allowed. Full size details shall be held to show actual finished sizes unless otherwise stated.
4.3.3 Moisture Movement
Precautions shall be taken, as far as possible to minimise the effect of moisture movement. These may include sealing the ends and concealed faces of timber and the edges and faces of sheet materials and assembling with slotted fixings to minimise distortion.
4.3.4 Joints
Where joints are not specifically shown on the drawings they shall be of the recognised and accepted form for their location and purpose. All joints shall comply with the requirements of BS 1186: Part 2 in principle or detail. All joints shall be put together with a suitable adhesive or filler. All joints exposed to the weather shall be sealed, or otherwise protected to prevent the ingress of water. All nails, sprigs, pins, etc. are to be punched below the surface and stopped with putty in the case of joinery which is to be painted and with a suitable hard stopping matching final finish in all other cases.
Timbers are to be in one piece of the length required wherever possible.
Where joints in the length are unavoidable, timbers up to 75mm in depth are to be halved and timbers exceeding 75mm in depth are to be splay scar fed. Joints are to be so constructed that they will resist the stresses and transmit the loads to which they will be subjected and shall be to the approval of the Engineer.
Joints are to be accurately formed and tight fitting and secured with an adequate number of screws and nails of the correct length properly clenched at right angles to the grain, unless bolted joints are specified. The jointing surfaces of all connections exposed to the weather are to be thickly primed with approved priming paint immediately before the joint is made.
Wherever possible in brandering, battening and similar members' length joints shall be formed over the points of support.
All joints of architraves, skirting, etc., at angles shall be neatly mitred and all mouldings at tee inter-sections shall be neatly scribed. All joinery work which is to be painted is to be prepared and primed in accordance with the
specification immediately after it is ready for fixing. The jointing surfaces of all connections of joinery to be painted are to be thickly primed with approved priming paint immediately before the joint is made. Where external joinery has to have glued joints, an approved waterproof adhesive shall be used. All nail heads are to be punched and screws countersunk.
Where a bolted joint is specified, it is to be made with screw bolts with nut and two washers or as specified and approved. Nuts are to be well tightened but not to the extent of damaging the timber under the washer.
4.3.5 Nailing
Wire nails, unless otherwise specified, shall be of the greatest diameter practicable consistent with their spacing and the avoidance of splitting. Where necessary to avoid splitting lead holes of a diameter not greater than 80 percent of the diameter of the nail shall be bored. Nails which are described to be clenched shall be of a length not less than 10 mm greater than the total
thickness of the timbers to be fixed and the points shall be bent at right angles to the grain and hammered flush with the surface.
4.3.6 Screws
Woodscrews shall be of the length, gauge and type and at the spacing given in the drawings.
Alternatively and when not otherwise specified, screws shall be of a length to engage all pieces being fixed and give a point side penetration of not less than seven times the diameter of the screw. Lead holes of a diameter not greater than 90 percent of the diameter of the root of the thread adjacent to the shank shall be bored for all screws and the screws shall be screwed home with screwdriver for their full length.
4.3.7 Fixing to Block work & Concrete
The whole of all timbers in carpentry work which are in contact with walls or concrete are to be thoroughly brush coated before delivery to site with two coats of wood preservative. All timber which is cut after being treated is to be re-treated with two coats of preservatives. Where carpentry or joinery work is to be fixed to concrete or block work, the latter shall have neat mortises made of the required depth which shall be plugged in accordance with the best practice ready to receive proprietary expanding plugs/bolts.
Ensure adequate penetration of masonry bolts into masonry; do not fix expanding bolts near edges of masonry; use resin anchors instead.
4.3.8 Bolting Bolts are as follows:
a) Use bolt lengths that will project at least one complete thread beyond the head of the nut without undue tightening.
b) Drill holes at right angles to the faces being brought together.
c) Drill holes slightly larger than bolt diameters unless timber has dried to the moisture level in service.
d) Use large thick washers under head and nut.
e) Do not split out the timber on the reverse side when drilling. If necessary to prevent this, drill from both sides after a small lead hole.
f) Tighten so that washers just compress the timber. Do not tighten so much that the washer or timber deforms.
4.3.9 Straps and Anchors
a) At each timber contact fix with a minimum of two screws when the number not detailed.
b) When strapping joists and rafters, and so on, use straps to span at least two members.
c) When strapping to masonry, block any gaps between timber members and masonry.
d) Ensure that any strap taken into a masonry wall cavity is turned down tight against the inner skin for an adequate distance.
e) When fixing straps to tops of masonry walls (for example, lateral restraint at gables) ensure that the fixing is not limited to a small masonry unit (such as a cut block, a single brick).
f) Ensure that all faces intended to be in contact are in close in contact without unspecified bending and improvisation.
4.3.10 Joist Hangers
Unless otherwise indicated, use screw-to-wall hangers. Select hangers of the correct size to fit the timber and to suit the loadings. Fix as follows:
a) With all supporting or fixing surfaces in close contact with the background and the timber being supported. A 6mm (max) gap is permitted between end of joist and hanger back plate.
b) Nail to the timber being supported through all pre-drilled holes.
c) Ensure joists are properly levelled and undertake any unavoidable notching carefully and accurately.
4.3.11 Framing Anchors
Subject to approval of the proposed type and locations, framing anchors may be used instead of timber joints.
4.3.12 Wall Plates
If possible fix wall plates in one piece between changes of direction; otherwise make 100mm lap joints. Bed in mortar truly level and fix with straps where necessary. Plug and screw or strap to lintels.
4.3.13 Bearings
Bear timbers in full contact on designed supports. Liberally coat with preservative ends built into masonry. Protect from contact with potentially damp surfaces and structures by DPC, where packing are necessary use material that will not rot or compress.
4.3.14 Fixing to Aluminium
Where aluminium components are fixed to joinery work, aluminium or cadmium plated steel screws and washers are to be used.
4.3.15 Exposed Fixings
All nails heads should be punched below timber surface which will be visible in completed work. Holes to be stopped with approved filler.
4.3.16 Pelleting
Countersink screw heads 6 mm below timber surfaces which are to be clear finished. Glue in grain matched pellets not less than 6 mm thick and cut from matching timber. Finish off flush with face.
4.3.17 Plugging
Locate specified plugs accurately into drilled holes for screw fixings to concrete, masonry and block work. Use proprietary plugs in accordance with the
manufacturer’s recommendations. When plugging through applied finishes ensure that plugs and fastenings have ample penetration into the structural backing.
4.3.18 Built in Joinery
Where joinery is described as “to be built-in” for setting it in position, plumb, level, brace and temporarily prop it so that it cannot be displaced during subsequent buildings operations. Provide and fix to the joinery any holdfasts, anchors or other fixings required to permanently fix it in the completed works.
If instructed by the Engineer, provide and fix protection pieces to edges and surfaces likely to be damaged during the construction process and remove them
If instructed by the Engineer, provide and fix protection pieces to edges and surfaces likely to be damaged during the construction process and remove them