Timer Decay

Question 1

What is the difference between wet & dry rot?

Answer 1

Wet rot is a number of different types of rot. Dry rot is one specific type of rot - Serpula Lacrymans.
Wet rot thrives in wetter environments than dry rot. Wet rot is generally relatively easily treated, dry rot can take extensive treatment. Wet rot can only survive while it has a food source, dry rot can survive dormant for long periods of time and can grow through masonry and plaster.

Question 2

What are the characteristics of wet rot?

Answer 2

Wet rot can have different characteristics. Brown rots can cause cuboidal cracking, and in some cases their fruiting bodies can have a purple hue (very rarely seen). The wood itself if damp and friable.

Question 3

What are the characteristics of dry rot?

Answer 3

Dry rot causes cuboidal cracking to wood, and will make a hollow sound when affect timbers are tapped. The mycelium are cotton wool like white strands, the fruiting bodies are like creamy pancakes with darker edges, and can weep in some cases. The fruiting bodies produce a rust coloured dust that can settle on horizontal surfaces in bad outbreaks. There is also a distinctive mushroom like smell.

Question 4

How do you treat wet rot?

Answer 4

To treat wet rot you must first remove the cause of the water. After that you need to remove all affected timber, ideally by a margin of 300mm past the first signs of affected timber. Any retained timber should be treated with a pesticide and removed timbers replaced with new.

Question 5

How do you treat dry rot?

Answer 5

To treat dry rot you must first remove the cause of the water. After that, as full inspection is required to establish the extent of the infestation. All affected timber should be removed, and 500mm past last sign of infestation. Surrounding plaster should be removed, and 1m past last sign of infestation. Removed timber should be burnt of site to ensure that wood is not reused. Surrounding timber should be treated, and it may be necessary to irrigate masonry walls etc. All removed timbers should be replaced with new.

Question 6

What is the optimal temperature of dry rot?

Answer 6

20 degrees C

Question 7

What is the optimal temperature for wet rot?

Answer 7

23 degrees C (can grow from -30 - +40)

Question 8

What is the optimal moisture content for wet rot?

Answer 8

Over 43%

Question 9

What is the optimal moisture content for dry rot?

Answer 9

20-30%

Question 10

Name three types of insect that attacks wood?

Answer 10

Common furniture beetle, deathwatch beetle, woodboring weevils

Question 11

What is the rot cycle for dry rot?

Answer 11

Spore on timber, spreads strands of mycelium, once established produces fruiting bodies, fruiting bodies produce spores (repeat)

Question 12

What times of year would you expect to find common furniture beetle?

Answer 12

May to September, you would expect to find frass and flight holes

Question 13

What are the treatment options for insect attack?

Answer 13

• Liquid treatment
• Paste treatment
• Gas fumigation
• Smoke treatment
• Heat sterilisation

Question 14

What is involved in liquid treatment for insect attack?

Answer 14

• Kills larvae in zone of penetration, and leave a zone of persistence layer to kill emerging adults and future infestations
• Either organic solvent based or emulsion based (water)
• Option to penetrate to deeper greater depth
• Emulsion is only suitable for common furniture beetle

Question 15

What is involved in the paste treatment for insect attack?

Answer 15

• Same as liquid applied, but gelatinous emulsion paste
• It provides greater penetration, but is a lengthier process
• Can stain/bleach the timber

Question 16

What is involved in gas fumigation as a treatment for insect attack?

Answer 16

Must enclose the timber completely, therefore is only suitable for moveables like furniture

Question 17

What is involved in smoke treatment for insect attack?

Answer 17

• Can be good for hard to reach places
• Requires repeat treatment
• Cannot be highly controlled, so effects not just the timbers

Question 18

What is involved in heat sterilisation as a treatment for insect attack?

Answer 18

A temperature of 52-55’c for 20-60 minutes can be effective. Difficult to achieve, and like smoke treatment effects everything unless done in a controlled situations with moveables