Timber Treatments

General Guide

It should also be noted that the Control of Substances Hazardous to Health Regulations (COSHH) 1988 may apply to the use of timber preservatives at work.

The following give a general guide to preparatory works to be undertaken as appropriate before treatment commences.

NOTE 1 Prior to any work being carried out the structural integrity of timber, etc., should be determined. If in doubt a structural engineer should be consulted.

NOTE 2 Remember!! dust is your enemy. always wear a dust mask when removing loft insulation, etc.

Preparation

Remove all floor coverings, furniture, etc, and any other items which may affect working practice. Cover any vulnerable materials, etc, which could be damaged. When moving or removing insulation, etc, ensure appropriate protection, eg, dust mask, etc. Isolate electrical circuits in treatment area. Ensure pvc, rubber coated cables and any similar material/items are protected from the remedial spray/formulation.

Roll up or remove roof insulation and clean between joists, etc, to ensure good access to timbers for the preservative. Cover water tanks thoroughly with polythene sheet. Sheeting may also be required to protect some areas against potential run off of preservative.

Ensure that all naked lights are extinguished.

Immediately Prior to Treatment

Exclude all persons not involved in the treatment processes from the immediate area both during and immediately after operations. Post warning notices at strategic points to prohibit smoking, and to identify that chemical treatments are being applied.

Ensure that written details are given to persons subsequently occupying treated areas, or persons who could be affected by fumes (i.e., adjacent properties), describing immediate steps to ensure a pleasant living environment, eg, ventilation, any short term safety requirements.

Treatments

Floors

Carry out all repairs deemed necessary. Where new timber is to be re-instated ensure that it is treated with a suitable preservative (preferably by one of the full cell impregnation processes).

Reinstatement of sound old wood should be treated by a minimum of a thorough surface spray but preferably by steeping in the appropriate preservative.

Any cut ends of reworked wood should be liberally treated with preservative prior to refixing. Lift sufficient floor boards to expose joists, joist ends and wall plates. Where the subfloor void is of sufficient size treatment may be applied from below without removal of boards.

Expose and clean down joists, joist ends, and wall plates and remove any severely infested wood (defrass).

Remove any debris from site. Apply preservative. Treat all exposed infested/vulnerable timbers thoroughly including floorboards.

Roof voids

Ensure that water tanks are covered. Remove insulation from areas to be treated. If necessary lift sufficient boards to expose joists, joist ends and wall plates. Expose and clean down joists, joist ends and wall plates and remove any severely infested wood (defrass).

Remove any debris from site.

Carry out all repairs deemed necessary. Where new timber is to be reinstated ensure that it is treated with a suitable preservative (preferably by one of the full cell impregnation processes).

Reinstatement of sound old wood should be treated by a minimum of a thorough surface spray.

Any cut ends of reworked wood should be liberally treated with preservative prior to refixing.

Apply preservative as described. Treat all exposed / infested / vulnerable timber thoroughly including floorboards.

Staircases

Remove any lining, if present, from the undersurfaces to obtain access to stair risers, or drill holes in risers ready for insertion of backspray nozzle.

Carry out all repairs deemed necessary. Where new timber is to be reinstated ensure that it is treated with a suitable preservative (preferably by one of the full cell impregnation processes).

Reinstatement of sound old wood should be treated by a minimum of a thorough surface spray but preferably by steeping in the appropriate preservative. Any cut ends of reworked wood should be liberally treated with preservative prior to refixing.

Apply preservative as previously described. Treat all exposed/infested/vulnerable timbers taking special care if using a back spray nozzle.

Application

Spray

Use a 'coarse' spray under a moderately low pressure to prevent 'atomizing' of the preservative.

Set nozzle/pressure to minimise bounce off of fluid from the timbers.

General rates of application are given as 1 litre per 4m2; in most cases this will require at least 2 treatments.

Normal spray to run-off will frequently give much lower application of fluid; this is especially important when considering planed wood, refractory timber (eg spruce) and old hardwoods (eg, large dimensioned oak). Vertical and underlying surfaces may also require extra application to obtain suitable loadings of preservative.

Brush

Three liberal brush coats should be considered equivalent to a good spray treatment.

Where timbers have a painted or vanished surface this must either be removed before treatment or individual flight holes should be injected directly.

Where timbers finished with decorative stains are to be treated test a small area prior to full treatment to ensure no discoloration of the finish.

Any timber, treated or not, may be at risk to wood rot if left in contact with dampness.