Weeping Willow, should it stay or should it go?

[MDC]

11 hours ago, PeterW said:

Sorry did we find out how far this willow is from the house ..?

 

Also - if you’re on piles today then it’s for a reason.. I would be more concerned with this first 

When the present house was built in 1953, there were no trees. The house sits at the top of a hill in a clay field. It was originally a bungalow, so it possibly safe to assume the foundations are shallow by today's standards. Why would it be on piles?

[PeterW]

Salix Alba within 15m of foundations on high plasticity soils (ie clay) would need 1.8m foundation with clay heave protection. Removing it would require the same foundations and treatment so why not leave it and go piled foundations …?

 

 

[PeterW]

35 minutes ago, MDC said:

so it possibly safe to assume the foundations are shallow by today's standards. Why would it be on piles?

Those 2 statements are conflicting - piles will be deep to get to a reasonable strata (assuming they are full piles..?) but could just be short piles and a reinforced ring beam to stop it moving on the clay.
 

Have you done any ground investigation ..? And have you exposed any of the pile itself ..?

[saveasteading]

5 hours ago, MDC said:

Less than 16 metres

If the tree was there when the house was built then it needed  footings of over 2m, or piles.

[MDC]

4 hours ago, saveasteading said:

If the tree was there when the house was built then it needed  footings of over 2m, or piles.

The tree was planted after the bungalow was built.

[MDC]

9 hours ago, PeterW said:

Those 2 statements are conflicting - piles will be deep to get to a reasonable strata (assuming they are full piles..?) but could just be short piles and a reinforced ring beam to stop it moving on the clay.
 

Have you done any ground investigation ..? And have you exposed any of the pile itself ..?

No ground investigation. I got the information from house plans. Thank you for your advice.

[Mr Punter]

I would remove the willow now and replace it with something that will not cause issues for your future plans.

[Jilly]

Am I being dim, but can the piles be reused, if you are building on the same footprint?

[MDC]

13 hours ago, Mr Punter said:

I would remove the willow now and replace it with something that will not cause issues for your future plans.

I now agree. I was looking at some Weeping Willows by the Thames yesterday. I thought the tree in question, by the house on my plot, is big, but I see it isn't by comparison, so if it stays, there will be considerably more trouble down the line. 

[MDC]

12 hours ago, Jilly said:

Am I being dim, but can the piles be reused, if you are building on the same footprint?

The new build will not be entirely on the same footprint.  You have me wondering if the original piles will be left in situ or dug out.

[PeterW]

25 minutes ago, MDC said:

You have me wondering if the original piles will be left in situ or dug out.

Usually chew or break the tops off about 8-900mm below ground and leave them - and hope they aren’t in the way of something ..!

[saveasteading]

With no offending trees you don't need to go deep, so piling should be unecessary (it is expensive). It might be worth incorporating the existing piles but it will depend on type of pile, the beam of slab design, and positioning. Good fun for your SE.

[Mr Punter]

My brother has a few willows in his garden.  His house is on clay soil and was piled about 25m deep.  He had an orangery fitted and just used a raft foundation.  A couple of years later disaster.  The orangery has now been removed, having settled so the doors would not open and it was causing damage to the house.

[saveasteading]

19 minutes ago, Mr Punter said:

about 25m deep

Not on clay surely? Perhaps if on silt.

4m would be usual in clay.

But yes, changing the foundation type so dramatically is likely to cause trouble.

[MDC]

51 minutes ago, Mr Punter said:

My brother has a few willows in his garden.  His house is on clay soil and was piled about 25m deep.  He had an orangery fitted and just used a raft foundation.  A couple of years later disaster.  The orangery has now been removed, having settled so the doors would not open and it was causing damage to the house.

Crikey, that's a story. Point noted.

[Mr Punter]

47 minutes ago, saveasteading said:

Not on clay surely? Perhaps if on silt.

4m would be usual in clay.

But yes, changing the foundation type so dramatically is likely to cause trouble.

 

Yes, clay, which is what caused the heave.  Probably silty clay and variable strata.  The house is on a hill but about 70 metres from a river.  They had to pile down to rock.

[saveasteading]

On 27/10/2022 at 18:14, Mr Punter said:

clay, which is what caused the heave.

 

Clay heave of the orangery with shallow founds, attached to an immovable house. Understood.

But I am unaware of clay heaving below 4m  as it should be constantly damp. Maybe a clay I don't know of. 

My point is not the differential movement but why 24m piles. I'd like to know if anyone can clarify.

Or perhaps the worry was more of the house sliding on the hillside. Is it steep?