hmpmarketing Posted January 18, 2017 Share Posted January 18, 2017 (edited) Hello everyone, Just got home from site, needed to vent out my frustration with some news from first BC visit so here I am! Today was the day we started marking out foundations (standard concrete), contractor organised a site visit with BC (private) at 15PM as he wanted to show him soil and if 1m deep concrete would be fine, we dug a hole 1m deep and waited for him to arrive. As soon as he arrived on site, he noticed that by the boundary of our plot there was a tree to the neighbours side, not really a big tree anyways. So he looks down at the hole and tells us that we would have to change the design due to being near that tree. He has requested a 2.1 deep foundation in the area surrounding it….so far so good, well more concrete so costs will be a bit higher than expected. Now came the surprising news: since we are going over 1.5m, any floor with a foundation below 1.5m needs to be suspended!!!! Don’t know how we missed this but we are now looking into having to go from standard concrete to beam and block can’t believe we only flagged this now, Im really down right now… Just looking for some consolation now and how much more I should expect to pay, although I do know it is more than a standard slab. Our house is a timber frame build, Im wondering if there is an alternative to this. Contractor will still go ahead with pouring concrete tomorrow for foundations, could anyone give me some good news? Thank you all, I need some hugs....... Edited January 18, 2017 by hmpmarketing Link to comment Share on other sites More sharing options...
ToughButterCup Posted January 18, 2017 Share Posted January 18, 2017 Erm, I'm just wondering whether your SE can present the BCO with some calculations? 1 Link to comment Share on other sites More sharing options...
ProDave Posted January 18, 2017 Share Posted January 18, 2017 Was a structural engineer involved in the design? Was it full plans approval? was the tree shown on the BC drawings? P.S imho nothing wrong with a suspended timber floor, that was my choice. 1 Link to comment Share on other sites More sharing options...
CC45 Posted January 18, 2017 Share Posted January 18, 2017 B&B didnt work out much more for us. Make sure its grouted in as soon as its down or it will just fill with rubbish. Quick and easy to lay. 2 Link to comment Share on other sites More sharing options...
hmpmarketing Posted January 18, 2017 Author Share Posted January 18, 2017 (edited) 29 minutes ago, recoveringacademic said: Erm, I'm just wondering whether your SE can present the BCO with some calculations? Hi recoveringacademy, well, we did submit all calculations to them previously, what should be demonstrated? No need to go that deep if Timber frame? 28 minutes ago, ProDave said: Was a structural engineer involved in the design? Was it full plans approval? was the tree shown on the BC drawings? P.S imho nothing wrong with a suspended timber floor, that was my choice. Hi ProDave, Yes, well the Timber Frame company (Dan Wood) provided all paperwork, Full plans approval, yes, Tree not shown, according to the the BC inspector, he said these things are "site specific" so hence why this was only flagged now 11 minutes ago, CC45 said: B&B didnt work out much more for us. Make sure its grouted in as soon as its down or it will just fill with rubbish. Quick and easy to lay. Mind sharing from who you supplied beams? My contractor said "Supreme Concrete" (http://www.supremeconcrete.co.uk/general/suspended-beam-and-block-floors/) would be the one most competitive in price Thanks again everyone Edited January 18, 2017 by hmpmarketing Link to comment Share on other sites More sharing options...
Ferdinand Posted January 18, 2017 Share Posted January 18, 2017 (edited) I wonder if @Sensus can help here? I hope there could be other ways round that, perhaps based on the type of tree and root spread / thirstiness etc. eg What happens if you put in a root barrier or bribe your neighbour to remove the tree? Ferdinand Edited January 18, 2017 by Ferdinand 1 Link to comment Share on other sites More sharing options...
hmpmarketing Posted January 18, 2017 Author Share Posted January 18, 2017 4 minutes ago, Ferdinand said: I wonder if @Sensus can help here? I hope there could be other ways round that, perhaps based on the type of tree and root spread / thirstiness etc. eg What happens if you put in a root barrier or bribe your neighbour to remove the tree? Ferdinand My wife gave that idea, bribe him for some £ and have the tree removed, there is no TPO on it as far as I am aware.... wondering if the cost would be for such a thing.... Regarding a root barrier, I think BC is more concerned with water demand for that tree..... Link to comment Share on other sites More sharing options...
Ferdinand Posted January 18, 2017 Share Posted January 18, 2017 Just now, hmpmarketing said: My wife gave that idea, bribe him for some £ and have the tree removed, there is no TPO on it as far as I am aware.... wondering if the cost would be for such a thing.... Regarding a root barrier, I think BC is more concerned with water demand for that tree..... You can but ask ... perhaps they want it removed, and if you gave them a specimen somewhere else... Link to comment Share on other sites More sharing options...
hmpmarketing Posted January 18, 2017 Author Share Posted January 18, 2017 8 minutes ago, Ferdinand said: You can but ask ... perhaps they want it removed, and if you gave them a specimen somewhere else... yea....food for thought! Link to comment Share on other sites More sharing options...
ProDave Posted January 18, 2017 Share Posted January 18, 2017 40 minutes ago, hmpmarketing said: Hi recoveringacademy, well, we did submit all calculations to them previously, what should be demonstrated? No need to go that deep if Timber frame? Hi ProDave, Yes, well the Timber Frame company (Dan Wood) provided all paperwork, Full plans approval, yes, Tree not shown, according to the the BC inspector, he said these things are "site specific" so hence why this was only flagged now Mind sharing from who you supplied beams? My contractor said "Supreme Concrete" (http://www.supremeconcrete.co.uk/general/suspended-beam-and-block-floors/) would be the one most competitive in price Thanks again everyone Did your SE not notice the tree? I ask, because we are building close to Willow Trees, which everyone will tell you are the worst. Our SE came to the site twice, and I dug 3 test pits for him down to about 2 metres deep, so he could assess the ground conditions. The only things he seemed to stipulate were that we dug down to the predominant sandy clay sub soil, and he specified a strong C35 concrete mix for the foundations and a heavy duty reinforcing mesh in the foundations. By the time I had stripped the organic top soil off the whole house site, and then dug the strip foundations, we were down to between 1.5 and 2 metres deep, but really the trenches from the stripped level were not that deep at all. building control just came and looked and said go ahead with the pour, because all they needed to know about the site, including the trees, was on the drawings. I have to say, I was surprised how few tree roots we encountered, and those we did find were tiny, but then the willow trees grow on the banks of a burn so let me guess where they might get most of their water from? Link to comment Share on other sites More sharing options...
PeterW Posted January 18, 2017 Share Posted January 18, 2017 Wouldn't matter if you remove it - heave takes up to 3 years. Three things you need to know : - soil type - tree type - distance to the tree From that you can use either the LABC or NHBC founds depth calculation to indicate the depth needed. That also indicates the compression foam requirement for the inner face of the founds as if it is 2.1m down then you need a minimum of 75mm compression void. And I'm not sure about the comment about being below 1.5m and suspended floor ..? Where is that from ..? 1 Link to comment Share on other sites More sharing options...
Ferdinand Posted January 18, 2017 Share Posted January 18, 2017 (edited) 8 minutes ago, PeterW said: Wouldn't matter if you remove it - heave takes up to 3 years. Three things you need to know : - soil type - tree type - distance to the tree From that you can use either the LABC or NHBC founds depth calculation to indicate the depth needed. That also indicates the compression foam requirement for the inner face of the founds as if it is 2.1m down then you need a minimum of 75mm compression void. And I'm not sure about the comment about being below 1.5m and suspended floor ..? Where is that from ..? Surely size of tree is also relevant. eg a 5m tree taken out now has fewer heave implications vs provisioning for the 30m tree it may turn into in 50 years? I also see - spelunking the 2010 regulations - that the foundation depth can be 50mm shallower each 50 miles North or West of London. Surprised ! Ferdinand Edited January 18, 2017 by Ferdinand 1 Link to comment Share on other sites More sharing options...
PeterW Posted January 18, 2017 Share Posted January 18, 2017 7 minutes ago, Ferdinand said: Surely size of tree is also relevant. eg a 5m tree taken out now vs dealing with the 30m it may turn into in 50 years? Nope it's entirely irrelevant ..! They do the modeling on the mature tree size unless you can prove an exception (which I've done with a pollarded oak) as unless it's on the plans for explicit removal then you can't enforce someone to take a tree out. Soil type is the bigger issue too - shrinkable clays can be a mare as they expand and contract for at least two growing seasons as the soil water levels readjust. LABC warranty guidance on trees is pretty good. 1 Link to comment Share on other sites More sharing options...
Ferdinand Posted January 18, 2017 Share Posted January 18, 2017 Just now, PeterW said: Nope it's entirely irrelevant ..! They do the modeling on the mature tree size unless you can prove an exception (which I've done with a pollarded oak) as unless it's on the plans for explicit removal then you can't enforce someone to take a tree out. Soil type is the bigger issue too - shrinkable clays can be a mare as they expand and contract for at least two growing seasons as the soil water levels readjust. LABC warranty guidance on trees is pretty good. Of course by the time it is through planning and got around to starting on site those 2 years may well have elapsed. F 1 Link to comment Share on other sites More sharing options...
hmpmarketing Posted January 18, 2017 Author Share Posted January 18, 2017 (edited) @PeterW so even if I get the tree removed now (neighbour permitted) I would not get away with BC now? spoke with neighbour just now and he would consider the thought..,,, Edited January 18, 2017 by hmpmarketing Link to comment Share on other sites More sharing options...
hmpmarketing Posted January 18, 2017 Author Share Posted January 18, 2017 1 hour ago, ProDave said: Did your SE not notice the tree? I ask, because we are building close to Willow Trees, which everyone will tell you are the worst. Our SE came to the site twice, and I dug 3 test pits for him down to about 2 metres deep, so he could assess the ground conditions. The only things he seemed to stipulate were that we dug down to the predominant sandy clay sub soil, and he specified a strong C35 concrete mix for the foundations and a heavy duty reinforcing mesh in the foundations. By the time I had stripped the organic top soil off the whole house site, and then dug the strip foundations, we were down to between 1.5 and 2 metres deep, but really the trenches from the stripped level were not that deep at all. building control just came and looked and said go ahead with the pour, because all they needed to know about the site, including the trees, was on the drawings. I have to say, I was surprised how few tree roots we encountered, and those we did find were tiny, but then the willow trees grow on the banks of a burn so let me guess where they might get most of their water from? @ProDave not really to be honest this is something that we completely ignored....argh! Link to comment Share on other sites More sharing options...
hmpmarketing Posted January 18, 2017 Author Share Posted January 18, 2017 Some info I missed posting: Tree height: around 5-6m; Distance to tree: about 1.3m; Soil Type: clay at deeper levels We are near the south coast, plot is 1.3km away from coast as the crow flies Link to comment Share on other sites More sharing options...
TerryE Posted January 18, 2017 Share Posted January 18, 2017 1 minute ago, hmpmarketing said: Tree height: around 5-6m, distance to tree: about 1.3m Ouch! I can see why the BInsp would cry foul on this one. You need to be careful with trees so close the foundations. Link to comment Share on other sites More sharing options...
PeterW Posted January 18, 2017 Share Posted January 18, 2017 Ok the clay is the issue there however at 1.2m for a moderate tree such as an ash, you still need heave protection at 2.1m depth ..! What has he proposed for the inner lining of the trench ..?? Block and beam removes the requirement for heave protection under the floor but that's still not considering the foundations. Have you got a warranty company involved as they may need something else. 1 Link to comment Share on other sites More sharing options...
nod Posted January 18, 2017 Share Posted January 18, 2017 4 hours ago, hmpmarketing said: Hello everyone, Just got home from site, needed to vent out my frustration with some news from first BC visit so here I am! Today was the day we started marking out foundations (standard concrete), contractor organised a site visit with BC (private) at 15PM as he wanted to show him soil and if 1m deep concrete would be fine, we dug a hole 1m deep and waited for him to arrive. As soon as he arrived on site, he noticed that by the boundary of our plot there was a tree to the neighbours side, not really a big tree anyways. So he looks down at the hole and tells us that we would have to change the design due to being near that tree. He has requested a 2.1 deep foundation in the area surrounding it….so far so good, well more concrete so costs will be a bit higher than expected. Now came the surprising news: since we are going over 1.5m, any floor with a foundation below 1.5m needs to be suspended!!!! Don’t know how we missed this but we are now looking into having to go from standard concrete to beam and block can’t believe we only flagged this now, Im really down right now… Just looking for some consolation now and how much more I should expect to pay, although I do know it is more than a standard slab. Our house is a timber frame build, Im wondering if there is an alternative to this. Contractor will still go ahead with pouring concrete tomorrow for foundations, could anyone give me some good news? Thank you all, I need some hugs....... Im surrounded by Ash trees So I brought a SE in prior to buying the plot Weve paid 4600 for 153 beamed floor and gone down 1,8 stepping up to 1.2 Plus a layer of over site for drainage 7 cube Including two d garages we have used 143 cube of concrete and removed 740 tons of spoil All this for a flat site on good firm ground Opposite a sand quarry Nice to have trees But expensive 1 Link to comment Share on other sites More sharing options...
hmpmarketing Posted January 18, 2017 Author Share Posted January 18, 2017 17 minutes ago, PeterW said: Ok the clay is the issue there however at 1.2m for a moderate tree such as an ash, you still need heave protection at 2.1m depth ..! What has he proposed for the inner lining of the trench ..?? Block and beam removes the requirement for heave protection under the floor but that's still not considering the foundations. Have you got a warranty company involved as they may need something else. Hi @PeterW He suggested block and beam, foundations 2.1m deep stepping up as we get further away from the tree. (still in doubt if I manage to convince neighbour in removing the tree would avoid all this trouble?) Regarding warranty, I did chase a quote, but we are not planning on selling anytime soon (in 10 years time), so not sure if I should bother 57 minutes ago, TerryE said: Ouch! I can see why the BInsp would cry foul on this one. You need to be careful with trees so close the foundations. Yea, I thought he was being too picky but I understand the concern Link to comment Share on other sites More sharing options...
PeterW Posted January 18, 2017 Share Posted January 18, 2017 28 minutes ago, hmpmarketing said: He suggested block and beam, foundations 2.1m deep stepping up as we get further away from the tree. (still in doubt if I manage to convince neighbour in removing the tree would avoid all this trouble?) No - trees are referenced for up to 3 years assuming they are "known about"... I've got both the LABC tech note and the NHBC one and both refer to compressible foam or a source of a heave protection down the inside of any foundation below 1.2m. I don't see how your BCO can ignore that as it has the potential to cause movement and it's against most of the guidance I've seen. You can use EPS40 as the foam - not expensive and easily installed but it needs doing before the founds are poured. I would also ask the BCO for his foundation design in writing - if he is private than god forbid if something goes wrong you have some sort of recourse..! 1 Link to comment Share on other sites More sharing options...
hmpmarketing Posted January 18, 2017 Author Share Posted January 18, 2017 @PeterW thanks for your insight, I will check this out tomorrow, wise words! So I should just forget the idea of removing the tree bite the bullet and pay for the extra cost :-( Link to comment Share on other sites More sharing options...
Onoff Posted January 19, 2017 Share Posted January 19, 2017 10 hours ago, PeterW said: Wouldn't matter if you remove it - heave takes up to 3 years. Three things you need to know : - soil type - tree type - distance to the tree From that you can use either the LABC or NHBC founds depth calculation to indicate the depth needed. That also indicates the compression foam requirement for the inner face of the founds as if it is 2.1m down then you need a minimum of 75mm compression void. And I'm not sure about the comment about being below 1.5m and suspended floor ..? Where is that from ..? I think I know what it is but what is heave? Guessing it's if you remove a large tree the roots the ground gets "looser", then takes a while for things to compact down again. I guess then the reduction in ground preassure can give rise to subsidence type issues etc. Seen similar where cable trenches get dug "to the garage" then the block paving sinks along that line. Link to comment Share on other sites More sharing options...
Ferdinand Posted January 19, 2017 Share Posted January 19, 2017 Ouch. 1.3m is seriously close, I am afraid. Link to comment Share on other sites More sharing options...
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