Preventing rot in end of floor joists

[charlieboy]

I am replacing some of the floor joists in the oldest part of my house. Where the joists went into the stone wall they were completely rotten. 4 or 5 hundred years of wet rot, wood worm and death watch beetle and a leaking roof had turned them into what looked more like potting compost than oak!
The new ones will be treated with preservative.
Would there be any advantage in wrapping the ends in plastic where they go into the wall or would this make matters worse?
Lead would be nicer but I don't think my budget would stretch to that.

 

[Ebenezer]

You'll probably be ok for another 500 years or so won't you?

 

[malcolm]

I don't think there will be any advantage of plastic wrapping. My understanding is the ends of the joists are cold where they fit into the wall and attract condensation from inside the house. Allowing the joists to breathe a little through the wall to help them dry out should be an advantage.

Of course if they are ground floor listen to others.

 

[MatthewC]

I had that problem in this house. It was caused by three things:
1. There was a concrete path outside, right up to the wall at floor level
2. The plasterers (in about 1860) had plastered down to the floorboards without leaving a gap between the plaster and floorboards.
3. There was no ventilation under the floor - only one vent which was blocked by cement!
All these issues were fixed before I moved in. Although I haven't checked whether the new boards have a problem, the entire house is nice and dry now. I suggest you check that your leaking roof was the only cause, and then they will survive for ages.

 

[88v8]

I would ensure that the ends are not in contact with the wall.
Where the joists sit on the wall, sit them on a bit of lead.
The cost of a roll of Code 3 lead - about £20 for 20ft of 4" - is relatively trivial, and will confer longevity on many aspects of the period house.

Ivo

 

[Matt Green]

Oak heartwood in a dry shouldn't need to be isolated, but packing the sockets with slate or lead would certainly do no harm.

 

[charlieboy]

Thanks for your thoughts.
What I should have said is that these are first floor joists (not ground floor).
I will try and post some photos tomorrow.

 

[charlieboy]

Photo as promised.
Has anyone got joists that are more rotten than this?

Oops! can't post it. Message says "Sorry, the board attachment quota has been reached." whatever that means!

 

[MatthewC]

What I should have said is that these are first floor joists (not ground floor).

In which case why was the wall so wet for so long? The ends won't rot if it's dry.

Oops! can't post it. Message says "Sorry, the board attachment quota has been reached." whatever that means!

Go to "User Control Panel" and "Manage Attachments" and delete some old ones. Or use Photobucket/Flickr etc as a link.

 

[charlieboy]

"In which case why was the wall so wet for so long? The ends won't rot if it's dry."

The wall was so wet because someone built a parapet and then did not clean out the gutter behind it for 200 or more years!

"Go to "User Control Panel" and "Manage Attachments" and delete some old ones. Or use Photobucket/Flickr etc as a link."

Thank you Matthew.

The second photo shows the centre beam and the notches cut into it to take the joists. Is this typical? Or does it tell us anything about the age or status of the building?