PRESERVATION MEASURES TO REMEDY FROM TIMBER ROT
Jan 26, 2016
PRESERVATION MEASURES
TO REMEDY FROM
TIMBER ROT
Common used engineering materialCommon used engineering material
Has less strength in green Has less strength in green
Strength can be increased by Strength can be increased by seasoningseasoning
Shrinkage should be eliminated before Shrinkage should be eliminated before useuse
INTRODUCTION
Alternate dry and wet conditionsAlternate dry and wet conditions
Defective seasoning of the timberDefective seasoning of the timber
Fungi developing diseases such as rotsFungi developing diseases such as rots
Insects such as marine borers, beetles, Insects such as marine borers, beetles, termites etctermites etc
Lack of ventilationLack of ventilation
Dark and damp conditionsDark and damp conditions
DECAY OF TIMBER
Decay of timber is not chemical action Decay of timber is not chemical action
Timber in dry and well ventilated place Timber in dry and well ventilated place or continuously submerged under fresh or continuously submerged under fresh water last for long timewater last for long time
Wood embedded in ground should be Wood embedded in ground should be treated with creosote, coal tar or treated with creosote, coal tar or chemicalschemicals
Rots disintegrate timber and produce Rots disintegrate timber and produce HH22S and COS and CO22 gases gases
DECAY OF TIMBER
Rot due to certain fungi which feed on wood and convert them into fine powder
Dry rot is due to certain species of fungi
DRY ROT
DRY ROT IN SUB FLOOR VOID WET ROT IN SUB FLOOR VOID
not properly seasoned timber
warm moist conditions
confined atmospheric condition
unseasoned timber if tarred, charred or painted
DRY ROT
Decomposition of timber due to moisture where timber converts into grayish brown powder
Some reasons for wet rot are:
alternate wet and dry conditions
unseasoned timber exposed to rain and wind
WET ROT
Protect timber structure from attacks of fungi and insects, borers, termites and marine organisms
Prolongs the life and durability of timber structures
Preservatives are painted, sprayed or impregnated
PRESERVATION OF TIMBER
Most efficient means is good seasoning and free circulation of fresh air
Leaks in water supply pipes, rain water and drains should be avoided
Timber should be kept dry during construction and also protect timber from getting damp after construction
PRESERVATION OF TIMBER
Prevent dampness to timber floor (DPC) and ventilate the space below and around the timber floor
Exposed timber can be preserved by impregnation of poisonous chemicals to fungi
Protect against moisture by oil paint
PRESERVATION OF TIMBER
There are three types of There are three types of preservativespreservatives:
i. Oil typei. Oil type
ii. Chemical (organic solvent) and ii. Chemical (organic solvent) and
iii. Water soluble preservativesiii. Water soluble preservatives
Coal tar, oil paints, creosote oiCoal tar, oil paints, creosote oil are are most common used preservativesmost common used preservatives
PRESERVATIVES
Should be cheap, durable, unaffected by heat and light, non combustible and easily available
Smell should not be very unpleasant
Safe
Should not affect strength and outlook
Should offer high resistance to moisture
Should efficiently kill fungi and insects
QUALITIES OF PRESERVATIVES
Charring Charring – Kept wet for ½ - 1 hrs and – Kept wet for ½ - 1 hrs and then burnt to depth about 15mmthen burnt to depth about 15mm
TarringTarring – Applying hot tar in the – Applying hot tar in the surfacesurface
- Mainly used for submerged surfaces- Mainly used for submerged surfaces
PaintingPainting – Makes timber beautiful and – Makes timber beautiful and also prevents white ant attack also prevents white ant attack
METHODS OF PRESERVATION OF TIMBER
In sewers / drains made from concrete, the sewer acids causes corrosion of concrete
Ground water with concentration of alkaline salts is harmful to sewer pipes
Sulphate resisting cement or high alumina cement is recommended
Seawater has same effect
Mixture of air and sea water rapidly corrodes concrete and steel
CORROSION OF CONCRETE
Protection
lining pipes with clay tiles
using stoneware pipes
jointing materials can be from resisting cement or high alumina cement
Use of coal tar or bitumen
CORROSION OF CONCRETE