Timber worksurface Installation Guide, Storage & base unit installation

Section 2: preparation of 27 & 40mm worksurface blanks and semi-processes components

For Worksurface Blanks and Semi-processed Worksurface Compoments there is a series of operations that must be carried out before they can be installed.

Bespoke timber tops come ready to install: pre-cut to size and shape; fully moulded, cut-out and grooved; jointed, edge sealed and oiled, but please read through this section to check and understand the principles of wooden top installation.

2.1 Setting out

Set out the worksurface so it has a 4-5mm expansion gap between its rear edges/ends and the wall surfaces.

2.2 Upstand

Upstand (if used) fits along the rear edges of the top and adds 10mm to its depth. It may be necessary to trim the work surface accordingly. (See Part 2, Section 5.3 for installation details.)

Upstand design 3 is for use with timber counterback units as well as on its own. The back edge of the work surface will need notching for the upstand adjacent to where the counterback is fitted. (See Part 2, Section 4.3).

2.3 Worksurface depths

The recommended finished depth of top is 610mm on 560mm deep base units with 20mm fascias – 620mm on 570mm base units, ect, ie. An overhang of 30mm. But considering most walls are uneven we would recommend 650mm and scribe to wall where necessary.

2.4 Corner joints

a) These must be butted or made with full equal mitres in order to accommodate crossgrain movement of the timber.

NEVER use a haunched mitre to join tops.

Each joint should be held and aligned with at least 3 work-surface bolts and 4, size 20 biscuits (not dowels).

Mitre joints:

b). Mitre joints are only suitable for 27 & 40mm thick tops.

DO NOT joint 60, 80 & 100mm tops with mitres

Make mitre joints with an equal angle. Reinforce the underside of the joint with a plywood or metal plate.

Screw fix the plate through slots (aligned across the woodgrain) at 12mm holes with pennywashers – to accommodate crossgrain movement of the worksurface timber.

Note:

The endgrain on worksurface joints and the holes for the bolts must all be edge-sealed during assembly. (See Part 2, Section 2.14a)

Tap plinths, end caps & scribing

2.5 Tap plinths

Joints between tap plinths and adjacent tops must be made with work-surface bolts.

Seal the endgrain at both sides of the joint with Endgrain (See Part 2, Section 2.14a).

Seal the joint with low modulus silicone sealer when the parts are finally to be tightened up.

2.6 End caps

Cut and fit end caps next to Agas, boilers and other hot appliances that run continuously or for long periods of time. They are also necessary on tops adjacent to dropped hobs. The caps reduce drying of the main timber part.

Attach securely with biscuits or loose tongues and waterproof woodglue, eg. Casamite.

2.7 Appliances

Leave 15mm gaps between the ends of tops and freestanding appliances, boilers, cookers, ect.

In every case follow the appliance manufacturers’ installation instruction.

2.8 Scribing and fitting

Any holes, notches or slots to clear pipes and other intrusions from the building should be at least 5mm larger all round than the intrusion.

Take care to avoid any contact between timber and intrusion after installation.

The timber edges must be smoothed and sealed with edge sealer. (See Part 2, Section 2.14a).

2.9 Sink and appliance cut-outs

Take great care when installing sinks into timber worksurfaces, due to the possibility of water penetration into the joints and timber if incorrect procedures and materials are used.

When positioning and making a cut-out for a hob always follow the manufacturer’s instructions for sizes, safety clearances, ect.

Observe minimum distances:

• From cut-out to end of joint - 100mm, except Belfast type sinks.
• From Belfast type cut-out to end of top = 300mm min.
• From front or back edges = 50mm

• Between adjacent cut-outs = 100mm min, and this narrow strip must be supported beneath with a rail.

Cut-outs for lay-on sinks and hobs must have a clearance of 3mm per side, 6mm overall, for cross grain timber movement.

Do not make square corners unless unavoidable, eg: for lay-on hobs.

Undermounted sinks should have an overhang of 7.5 – 10mm all round.

For accuracy, quality and safety cut-outs for undermounted sinks should be bench-cut using jigs and a router, never a jig saw.

Prepare the work surface to take the sink fixing clamps at the same time as the undermounted cut-out is being made.

The edges of all concealed cut-outs for lay-on sinks and appliances and tap holes must be smoothed and thoroughly sealed with Edge Seal.

This will prevent damage to the timber from condensation and any leakage.

Please tell the plumber of the requirement to seal all concealed edges against moisture.

Belfast type sinks & trial fitting

2.10 Belfast type sinks

These sinks should have overhangs of 10mm at side and back. The depth of the cut-out should allow the sink to project at the top front edge, by half the sink wall thickness.

The cut-out for the sink should overlap the edges of the sink by half the thickness of the sink’s back and side walls.

For accuracy, quality and safety Belfast sink cut-outs should be benchcut using jigs and a router, never a jig saw.

2.11 Flush mounted sinks

Do not install flush-mounted sinks into timber worksurfaces. This is a specialist fabrication with adhesives and techniques to suit and must not be undertaken on site.

2.12 Trial fitting

Put all the pieces of worksurface onto the base units for a trial fitting.

Remember to include the 4 – 5mm expansion gap between the edges and ends and the walls.

Check that everything is good before fixing down the tops, including:

• The final postion of any Belfast sink (See Section 2.10 above)
• The relationship of any cut-outs to their base units – where front rails may need to be cut away or refixed vertically.

Make any adjustments as necessary.

Edge sealing worksurface oiling

2.13 Belfast type sink, installation

Position the sink as directed in Section 10 above. Fix it to the base unit by bedding the sink onto beads of low modulus silicone.

Leave it to set.

2.14 Edge sealing and worksurface oiling

All unfinished timber surfaces: edges, ends, top and bottom faces, must be edge sealed as necessary and oiled before installation.

Clean off any marks and smooth any roughness from the timber using a minimum 150 grit abrasive paper before sealing and oiling.

a). Edge Seal

All concealed edges: under lay-on appliances and sinks, around tap holes, fitting notches and slots, also concealed endgrain on tap plinth, butt and mitre worksurface joints must be sealed before installation.

Use edge sealer or Cascamite resin wood glue. Apply a liberal coat of either and allow it to cure before assembly. Silicone is unsuitable for this operation.

Note:

Wipe off any overspill from the visible surfaces and when dry, sand the clean with 150 grit paper. This prevents the edge seal from affecting uptake of the worksurface oil finish.

b). Worksurface oil

All other unfinished surfaces: top, bottom, edges and ends, must be oiled before installation with oil. Apply 3 coats to all surfaces and edges. Let the oil dry thoroughly between coats.

Apply 5 coats to all visible endgrain, paying particular attention to cut-outs for undermounted sinks.

Follow the directions on bottle.

With semi-processed timber worksurfaces there may be a discrepancy in colour between the pre-finished and newly finished parts of the wood.

This is quite normal and will quickly disappear as the new surfaces weather in service.