Timber worksurface planning & specifying

Section 5 : planning & specifying

Section 5 : planning & specifying

Manufacture requires a clear, well detailed, fully dimensioned drawing or sketch plan of the whole top installation.

Top parts that have a lot of information are best drawn out separately, in addition to showing these in the overall drawing of the installation.

A thumbnail sketch is also useful to show how the tops relate to the surrounding walls and any tall base units.

Note: Heaters and radiators

Timber worksurfaces should not be installed over radiators or other heating devises. The constant heat will cause excessive drying out and shrinkage of the worksurface underside and could result in the warping and splitting of the timber.

5 . 1 Layout

Start by drawing out the base unit plan. Include corner off-sets and applied end panels. Calculate and draw in the positions of cut outs and bars for hobs, sinks, ect, on this base unit plan. Remember to observe minimum distances from edges. (See Section 4). The work-surface plan can then be superimposed over this base plan. See work-surface plan checklist below.

5 . 2 Corner angles

On Site:

Measure the angles between adjacent walls for any external and internal corners where tops are to be fitted.

Take these measurements at the height at which the worksurface will be installed.

All corners will be cut at 90º unless specified otherwise.

Angles should be shown as offsets from square in millimetres across given distance, eg. 103mm for a work surface depth of 615mm.

Take the measurements as if they are to be butt jointed. Allowance for butt & scribe or full mitres will be added at manufacture.

Mark the offsets onto the work surface drawing or send them in the form of full size templates with the drawings.

Template method 1.

Make template from strips of board, each at least 650mm long with a brace. Measure the offset & use it on the drawing or send the template in if it is strong enough.

Template method 2.

Use a square piece of board to mark or cut the angle onto. Measure the offset & use this in the drawing or send the template in.

Note: Make templates out of hard board, ply chipboard or mdf. Not cardboard or paper.

5 . 3 Flatness of walls

Use a long straight strip of board or timber to test the flatness across wall surfaces. Unevenness, especially convexities, may affect the angle at which work-surface pieces meet in corners.

Small gaps from an irregular wall surface will usually be covered by the thickness of wall tiling.

Otherwise, the rear edge of a top can be scribed to the uneven wall: the ‘modular’ top depth is 615mm, which includes a nominal 5mm for scribing. Never chase a wooden top into a wall surface!

Scribing can be done either on site as part of the installation ( the timber’s waterproof finish must be fully re-installed over smoothed timber before the top is fixed in place), or the rear edge can be shaped during manufacture of the top parts. Specify the scribed shape either by measuring and marking it onto the drawing of the top or by providing a full size template.

Note:

The overall depth of the top may need to be increased to maintain adequate overhang along the front edge.

5 . 4 Notching and slotting

The back edge of worksurface can be notched and slotted to clear pipework and other protrusions from the wall. Allow fitting and expansion clearances of at least 5mm all round.The cut-out edges will be fully sealed against moisture.

5 . 5 Installation gaps

Timber worksurfaces must be installed with a clear 4 – 5mm gap between their edges or ends and adjacent wall surfaces. The gaps serve two purposes: they prevent a moisture bridge forming by contact of the timber with the wall surface; they allow natural movement of its timber as it expands and contracts across its grain in response to changes in humidity of the environment.

Installation gaps must be incorporated into the finished sizes of the timber worksurface. This is of particular importance on tops to be installed between opposing walls or between a wall and tall units.

The gaps can be concealed behind an upstand, or by the thickness of wall tiling or splashback, or by filling with low modulus sealer.

5. 6 Work-surface Plan, checklist

a) Draw the work-surface plan separately so that it will fit onto the base units (as drawn at stage 1 above). Include the required overhangs at front and ends and any installation gaps for the kitchen walls.

Show any upstand in place.

Remember that upstand adds 10mm to worksurface depth. Adjust the worksurface depths as required. Make the drawing large enough on one or more sheets of A4 paper to be able to show all the small detail clearly.

b) Put overall dimensions to the worksurface (but excluding upstand thickness) around the outside of the drawing , lengths and depths.

c) Transfer the dimensions for appliance and sink cut-outs from the base unit plan onto the top plan – add top overhangs as necessary. Use the front edges and one end of each top as datum points to run the measurements from. Do not forget to show corner radii, ect.

If templates for cut-outs are being provided, precisely indicate the positions for these on the top plan.

d) Mark centres and diameters for any tap holes.

e) Indicate which edge mouldings are required by labelling each edge and end. Show where the moulding is to run the whole length of the edge/end and where it is to stop.

f) Show the type of corner joint required butt, butt & scribed or full mitre. (Their selection is determined by the edge mouldings).

g) Mark any angle that is not 90º, by the offset from square in millimetres, or indicate where corner templates supplied are to be used.

h)Show any slots or notches at the back edges of the worksurfaces, also any shaping needed for irregular walls.

i) Show corner/ end shaping as required.

j) Show the upstand: state the number of 3000mm pieces that are required together with any upstand shaping.

k) Supply a thumbnail sketch of the room plan with 0/ all dimensions and main features for the top plan to be checked against.

l) Clearly mark: the drawing with the drawing with the specifier’s /customer (your) name and a contact number. Show the business name, job number/client name and the scale if applicable.

m) Mark the species and thicknesses that the tops are to be produced from.