Preventing further or future rot

[Lower]

I have a porch with two large wooden pillars that are starting to rot at the bottom. They've been there for circa 90 years so they are not doing too badly but the previous owners slabbed over the original raised porch floor with slate and cemented up to the pillars.

It looks like this is leading to them sucking up moisture and starting to rot or certainly making any rot that was there worse.

Photos below:

At the moment the rot isn't serious so i can cut it out, scarf in some new wood and repaint but i'd like to know what i can do where they meet the slate to prevent the rot from reoccurring.

All help much appreciated.

 

[foxhole]

In large wood framed buildings they often use stainless steel feet to timber uprights to keep them away from ground moisture, you could cut off base and replace with steel foot.

 

[Lower]

That would involve lifting slabs etc which i was hoping not to do. I was hoping for advice along the lines of waterproofed cement around the base or some sort of rot resistant treatment to the wood prior to painting.

 

[JohnD]

a common approach is to prop up the porch, taking the weight off the pillars (maybe also lift it half an inch), saw off the bottom off the posts (maybe six inches above ground level to avoid water spash, or as high as you need to get to unrotted dry timber

than chip out the rotten wood from the hole and cast a concrete foot, with a raised concrete pad (use a wooden form to make it neat and square) for the wooden pillar to sit on. Using a steel socket on the pad will prevent the pillar moving if it is knocked hard, and will provide a gap to prevent water transmission.

Put the bottom of the pillar in a plastic tub of wood preserver (I use spirit-based cuprinol) to soak for several minutes at least into the end grain of the post. It can be painted when fully dry.

If you have to cut off a substanial amount of the old post due to rot, soak the replacement stump in preserver as well, especially the ends.

I prefer to use stainless screws for external timber that is exposed to weather that you want to last for many years.

Remove the props only when the concrete has had a week to harden and cure.

 

[foxhole]

That would involve lifting slabs etc which i was hoping not to do. I was hoping for advice along the lines of waterproofed cement around the base or some sort of rot resistant treatment to the wood prior to painting.

Lifting slabs would not be required as base plate would straddle them.

 

[Lower]

a common approach is to prop up the porch, taking the weight off the pillars (maybe also lift it half an inch), saw off the bottom off the posts (maybe six inches above ground level to avoid water spash, or as high as you need to get to unrotted dry timber

than chip out the rotten wood from the hole and cast a concrete foot, with a raised concrete pad (use a wooden form to make it neat and square) for the wooden pillar to sit on. Using a steel socket on the pad will prevent the pillar moving if it is knocked hard, and will provide a gap to prevent water transmission.

Put the bottom of the pillar in a plastic tub of wood preserver (I use spirit-based cuprinol) to soak for several minutes at least into the end grain of the post. It can be painted when fully dry.

If you have to cut off a substanial amount of the old post due to rot, soak the replacement stump in preserver as well, especially the ends.

I prefer to use stainless screws for external timber that is exposed to weather that you want to last for many years.

Remove the props only when the concrete has had a week to harden and cure.

That all make sense.

However, the base of the post is only rotten around the edges, not to the core, so i'd prefer not to have to replace the whole of the bottom section. Unfortunately, because the slabs have been laid around the posts and grouted with cement up to the posts, the dampness is being transferred held by the cement in contact with the wooden post. It is that i want to get away from.

If i was to cut out the rot (which is just on the surface) and rake out the cement so that there is no direct contact between the slabs/cement and the post i could them replace the rotten wood with preservative treated new wood and then fill the gap around the base of the post with external silicone or similar to prevent the damp bridge that there is at present.

Does that sound reasonable?

 

[JohnD]

the base of the post is only rotten around the edges, not to the core

I bet it isn't.

 

[joe-90]

If it were me I'd make a 4x1 pressure treated skirt and chop it in flush.

Then drill a 10 mm hole above it at an angle down to the heart of the post and fill with solvent type rot fluid. Make a small plug for the hole which you can remove and refill with rot fluid every few months.

 

[Lower]

the base of the post is only rotten around the edges, not to the core

I bet it isn't.

It is. The slate slabs have only been down for 2 years.

 

[Harbourwoodwork]

Oak timber framer's would set the posts on saddle stones with stainless steel pin to hold in place