Help on foundation choices...

[matthyde83]

15 minutes ago, Buzz said:

Whatever route you choose to go down i would check on availability ASAP i was quoted 6 to 8 weeks by several companies for soil samples back in the summer,  most SE will do their own and then do the design your might have a bit of a shock as to when they can fit you in .

 

have SE lined up for steel work. They’re sorting it in next 2/3 weeks.  Just wondering whether I get them to do a design, which will then undoubtedly be over engineered compared to BC doing it on site.  

[matthyde83]

8 minutes ago, SteamyTea said:

Decide on the thermal losses and then work from that.

 

??  I can work backwards on depth and incorporate necessary insulation.  This isn’t the question really…

[nod]

12 minutes ago, matthyde83 said:

planners??

already has full planning and BC confirmed earlier they will happily deal with it on site. 
 

q is will structural warranty want more…

Answer is NO A Structual warranty company will need a foundation design 

So will the builder 
 

[Buzz]

8 minutes ago, matthyde83 said:

have SE lined up for steel work. They’re sorting it in next 2/3 weeks.  Just wondering whether I get them to do a design, which will then undoubtedly be over engineered compared to BC doing it on site.  

Thats good news for the steel work ?,  I can only comment on my experience of this, others on this forum will have forgotten more than I will ever know , I had a meeting with the builder and bc on site they both had their opinion on what would be the best way to do our foundations based on the soil report ,the bc had already passed the next door plots and had seen the soil survey for them and was of the opinion mine was unlikely to be any different but he would require a copy specifically for my plot , the warranty provider also said they could only inspect against what was recommended in the report but neither required a full design just a recommendation of how deep , wide and concrete strength. 

We had 4 holes drilled and recieved a report that stated 2 slightly different specs depending on solid concrete oversight or block and beam , there was a caveat in the report that stated the final depth of the foundations may have to be adjusted if during excavation any issues not picked up in the test holes became apparent. 

The warranty man was happy as long as he had a piece of paper he could inspect against,  I was happy that the local bc, builder and groudworker all agreed that will do nicely . 

[matthyde83]

5 minutes ago, Buzz said:

Thats good news for the steel work ?,  I can only comment on my experience of this, others on this forum will have forgotten more than I will ever know , I had a meeting with the builder and bc on site they both had their opinion on what would be the best way to do our foundations based on the soil report ,the bc had already passed the next door plots and had seen the soil survey for them and was of the opinion mine was unlikely to be any different but he would require a copy specifically for my plot , the warranty provider also said they could only inspect against what was recommended in the report but neither required a full design just a recommendation of how deep , wide and concrete strength. 

We had 4 holes drilled and recieved a report that stated 2 slightly different specs depending on solid concrete oversight or block and beam , there was a caveat in the report that stated the final depth of the foundations may have to be adjusted if during excavation any issues not picked up in the test holes became apparent. 

The warranty man was happy as long as he had a piece of paper he could inspect against,  I was happy that the local bc, builder and groudworker all agreed that will do nicely . 

ok… so I don’t have a soil report.  That seems like something I’m gonna need… BC and builder didn’t need it for garage.  They dug until they got to chalk.  BC knows the area well though and commented on that when I spoke to them earlier, told me to allow for 1.8m all round and I will be more than fine. 

[Buzz]

3 minutes ago, matthyde83 said:

ok… so I don’t have a soil report.  That seems like something I’m gonna need… BC and builder didn’t need it for garage.  They dug until they got to chalk.  BC knows the area well though and commented on that when I spoke to them earlier, told me to allow for 1.8m all round and I will be more than fine. 

The thing is if your bc doesn't require one (soil report) and you are happy with his judgement then the only reason to get one done is to satisfy the warranty provider who most likely will and getting a warranty is usually a condition insisted by your lender. 

[matthyde83]

2 minutes ago, Buzz said:

The thing is if your bc doesn't require one (soil report) and you are happy with his judgement then the only reason to get one done is to satisfy the warranty provider who most likely will and getting a warranty is usually a condition insisted by your lender. 

yep I’m going to call the warranty provider (that I think I’m going to use) in the morning to work out what’s needed.  It’s feeling very much like having a warranty is going to cost a lot more than the warranty fee!

[Blooda]

1 hour ago, matthyde83 said:

have SE lined up for steel work. They’re sorting it in next 2/3 weeks.  Just wondering whether I get them to do a design, which will then undoubtedly be over engineered compared to BC doing it on site.  

 

Not necessarily over engineered - we got a SE to design our foundations to take into account the known trees, and soil. [we had to have GI due to historic landfill, that was on the council records but they had no idea where it was, so it may have been on our plot.  His design measured in at 29 cubes of concrete.   We found some old roots so we went deeper,  Also smoothed out some of the steps. BCO wanted more out. We also didn't leave the indefeasibly small island of soil for the chimney.  Also he had an array of different widths that we didn't have buckets for, so we had to use wider ones. By the time we'd finished we had put 69 cubes in !   Luckily the ground worker [who I'd know for 20+ years] was on T&M

so it only cost me what is cost.  

 

Best thing is to get a price from the SE, or a couple, 

 

[matthyde83]

7 minutes ago, Blooda said:

 

Not necessarily over engineered - we got a SE to design our foundations to take into account the known trees, and soil. [we had to have GI due to historic landfill, that was on the council records but they had no idea where it was, so it may have been on our plot.  His design measured in at 29 cubes of concrete.   We found some old roots so we went deeper,  Also smoothed out some of the steps. BCO wanted more out. We also didn't leave the indefeasibly small island of soil for the chimney.  Also he had an array of different widths that we didn't have buckets for, so we had to use wider ones. By the time we'd finished we had put 69 cubes in !   Luckily the ground worker [who I'd know for 20+ years] was on T&M

so it only cost me what is cost.  

 

Best thing is to get a price from the SE, or a couple, 

 

Which again begs the question - why get it designed!  

[saveasteading]

5 hours ago, nod said:

SE normally air on the side of caution 

Well, we wouldn't  want them to cut corners, but over-designing should not happen either.

5 hours ago, nod said:

While conifers have shallow roots 

The take a lot of water out of the ground 

Causing Heave 

But a lot less than big deciduous trees. NHBC tables make it very easy.

[saveasteading]

5 hours ago, matthyde83 said:

How about this…

As I understand the drawing, the trees that would require deep founds are not near the building.

What are the conifers shown as blue circles, as that is crucial?

 

Having the name 'The Willows' is a bad start as they are among the worst water drinkers and the roots spread far.

 

However, I am amazed that you are contemplating not engaging an SE. 

We are here to help but not do free designs and take any risk off you.

 

The BCO will want drawings and calculations (and/or statements) to justify the proposal. They do not necessarily check very much anyway, and will expect to see expert design.

 

Re construction method. My hunch is that beam and block will cost you a little more, as you need more foundations.

Also you have lots of hardcore so that is a saving on an in-situ slab. I don't understand why that may not be suitable.

You have chalk and so there is no reason for foundations to go deep.

But there are many more factors, and we have not seen the site or drawings.

[Dave Jones]

13 hours ago, Declan52 said:

Saves them money.

 

 

 

 

 

 

Certainly does, easier as well if you do it properly with the right machinery.

[dpmiller]

not that any developer would care, but how much extra insulation thickness do you need to counteract the cold air under the  suspended floor?

[Blooda]

11 hours ago, matthyde83 said:

Which again begs the question - why get it designed!  

 

We got it designed as we were going down the turnkey contract route originally.  Also the warranty people want a design.  

[matthyde83]

9 hours ago, saveasteading said:

As I understand the drawing, the trees that would require deep founds are not near the building.

What are the conifers shown as blue circles, as that is crucial?

 

Having the name 'The Willows' is a bad start as they are among the worst water drinkers and the roots spread far.

 

However, I am amazed that you are contemplating not engaging an SE. 

We are here to help but not do free designs and take any risk off you.

 

The BCO will want drawings and calculations (and/or statements) to justify the proposal. They do not necessarily check very much anyway, and will expect to see expert design.

 

Re construction method. My hunch is that beam and block will cost you a little more, as you need more foundations.

Also you have lots of hardcore so that is a saving on an in-situ slab. I don't understand why that may not be suitable.

You have chalk and so there is no reason for foundations to go deep.

But there are many more factors, and we have not seen the site or drawings.

 

The blue circles are the hedge, the report has them labelled as western red cedar (they smell like bubble gum when you cut them).

Luckily although the house is called the willows there doesn't appear to be any willow trees!  Not that I've ever found anyway.

 

I'm just trying to work out what to do.  I have a structural engineer doing the steel work and question is do I get the foundation designed.

 

I've spoken to warranty provider I'm thinking of using this morning and their advice was to buy the warranty (shock) then they can engage the surveyors to look at everything and decide if it needs designing.  I hadn't purchased it yet as we are starting in February but it seems like the best course of action to be as prepped as possible rather than find out they want it designed two weeks before we're due to start on site!

[saveasteading]

22 minutes ago, matthyde83 said:

do I get the foundation designed.

So ask them for a price. This looks like being standard details so they may not charge much, it may allow a reduction in your warranty (and insurance?) costs, and the SE works for you so will discuss options if you ask.

[matthyde83]

4 minutes ago, saveasteading said:

So ask them for a price. This looks like being standard details so they may not charge much, it may allow a reduction in your warranty (and insurance?) costs, and the SE works for you so will discuss options if you ask.

 

I have just sent them an email ?

[saveasteading]

Have checked the effect of cedars. Moderate water demand, and growing to 20m.  therefore the house is too close to be unaffected.

However you are on chalk. The SE will more likely save you money in the long run.

[matthyde83]

9 minutes ago, saveasteading said:

Have checked the effect of cedars. Moderate water demand, and growing to 20m.  therefore the house is too close to be unaffected.

However you are on chalk. The SE will more likely save you money in the long run.

 

Thank you for that.  Yep I've asked the SE for a quote and what they need.  My issues I suppose is its not just the SE cost, I'm fully expecting soil sample as the next request etc.  It is what it is though, I'd rather know and do it now than come to a stop before I get going in Feb.

[saveasteading]

1 minute ago, matthyde83 said:

I'm fully expecting soil sample as the next request

If they are local they will know the ground types and not need lab tests. You can dig the holes in advance to save cost.