Worried that my house and garden are sinking

poorlittlefish

Some very odd things have been happening in my garden, now indoors too, which are making me worried that both are sinking/suffering from subsidence. 

1) Last summer, after the enormous amount of rain we had in the previous months, I noticed that my front patio was no longer level and had sunk in a few places, including around the edge of my conservatory.  At the time, this was put down to the patio base not being properly prepared
2) At Christmas I noticed similar issues in my rear garden, with the steps also cracked and not sitting flat.  The floor of the shed seemed to have sunk too. 
3) This past week I went into the loft and noticed that there were gaps in between the lengths of laminate flooring that were never there before and now the carpets/vinyl throughout the bungalow have ripples and I swear I can feel cracks and unevenness.  I'm useless at anything DIY, so can't work out how to lift up the carpets, let alone get them back again.

Is are all these odd things signs of subsidence?  There are no cracks in walls, but then from the inside all the walls are plasterboard.  I've not spotted any cracks on the exterior brickwork fascia.  My bungalow was built on sloping land and in an ex-mining area (the mine closed in 1959 and the Coal Authority survey from when I bought said the last claim made was in the 90s), so I don't think my odds are good.

chrisw

It's possible, but I think the seed has been sown in your mind and you're seeing issues which aren't really there. 

It's very rare for a house to sink evenly, you would certainly expect to see cracking along the external mortar lines, lintels, etc and along corners, ceiling joints, etc inside.  Temperature and humidity changes in the loft are likely to open gaps in laminate.

The only real way to put your mind at ease is to call in a structural surveyor but this is likely to cost around £500 to £1000.

tacpot12

While I agree with chrisw that the only way to put your mind at rest, or help you fix any problem you have, is to call a structural engineer, I am inclined to think that you can keep the cost done to £500 or less, if you explain that you don't need a written report at this stage, just a visual inspection and an opinion. Many surveyors will be happy to come out to site for an hour, examine the situation and give you benefit of their experience and knowledge for £4-500. It's relatively easy money for them, especially if they are happy when on-site that it is the homeowner being over-sensitive to normal movement. 

Even £400 might sound a lot for the time they are on site, but you are paying for knowledge and experience that takes time to acquire and for their professional indemnity insurance that means you can make a claim against them if they reassure you that there is no problem when in fact there was a problem. 

Doozergirl

tacpot12 said:

While I agree with chrisw that the only way to put your mind at rest, or help you fix any problem you have, is to call a structural engineer, I am inclined to think that you can keep the cost done to £500 or less, if you explain that you don't need a written report at this stage, just a visual inspection and an opinion. Many surveyors will be happy to come out to site for an hour, examine the situation and give you benefit of their experience and knowledge for £4-500. It's relatively easy money for them, especially if they are happy when on-site that it is the homeowner being over-sensitive to normal movement. 

Even £400 might sound a lot for the time they are on site, but you are paying for knowledge and experience that takes time to acquire and for their professional indemnity insurance that means you can make a claim against them if they reassure you that there is no problem when in fact there was a problem. 

This.  Initially you want advice. 

If the news isn't good then you'd probably want to move onto your insurers.  I think it's best to have an informed view before you contact them.  The news from your structural engineer might not be bad! 

Norman_Castle

"the carpets/vinyl throughout the bungalow have ripples and I swear I can feel cracks and unevenness"

If its a wooden floor that could be due to very high humidity.

In your loft do you mean loft flooring rather than laminate flooring?

poorlittlefish

Norman_Castle said:

"the carpets/vinyl throughout the bungalow have ripples and I swear I can feel cracks and unevenness"

If its a wooden floor that could be due to very high humidity.

In your loft do you mean loft flooring rather than laminate flooring?

The floors are concrete and with the loft, it looks like normal laminate flooring like you'd have elsewhere in the house.

Norman_Castle

Laminate flooring normally floats on top of a structural floor and is unlikely to be an indicator of movement. If the gaps are at the ends of the laminate boards they may have just slid apart if they're not contained at the ends. Try kicking them back together.

twopenny

"Try kicking them back together." now that's my sort of DIY

Often works.

Are all these things new? Is it possible the cracks in the steps were mended/covered and have reopened?

Start by dealing with putting the 'laminate' together again. That could just be the damp and cold making them move if they aren't secured. Lofts are vented on bungalows usually so temperature may be the reason.

Lino/vinyl flooring if not glued down could also be reacting to temperature.

You may not be diy savey but get yourself a spirit level from a diy shop, look at the levels as they are now, take a photo and then do it again in a few weeks. Compare the photos to see if the level is changing.

But we have had a ridiculously hot dry summer followed by eternal rain and cold. Could be when things start to dry up it won't look as bad as you think.

KJIWTIStructE

Hi, I'm a structural engineer and the first thing I look for at an inspection is cracking in walls, if you don't have any significant cracks visible externally then there is no need to panic.
Patios and paths etc are always liable to move, they are not built on a deep enough base to prevent seasonal changes in the ground causing movement. Your bungalow foundations should be deeper than the sub base for your patio but the age of the property does mean that these could be quite shallow in comparison to modern guidance on foundation depths. It's still standing after 60 years with no wall cracks so seems to be doing ok.
Laminate in a loft if unheated will definitely suffer thermal movement and will never indicate subsidence at ground level so disregard this entirely.
Subsidence is almost always due to volume changes in clay soil, they shrink in summer and swell in wet periods, this can cause houses to move up and down if the foundations are shallow, it can also cause floor slabs to move if they are ground bearing, which they shouldn't be if on clay.
If you Google bgs or british geological survey then their website has a map viewer that you can put your postcode in and it will show what the local soil types are, if you find clay in the area then it's worth investigating further. Mature trees close to houses also greatly increase the magnitude of volume change in the clay, making shallow foundations more prone to movement. If it's not clay soil the other possibility is broken drains washing out fine particles in a granular soil, which doesn't expand/contract like clay but can get washed out causing similar movement but this is less common. I would advise not rushing in and paying for an inspection yet, have a good look around the external walls to see if any cracking can be seen, this could follow mortar joints between bricks or be more noticeable if close to large trees if you have any nearby. If there are none visible then subsidence should not be an issue on your bungalow. Good luck!

Annemos

My bungalow is 40 years old. It was hit with Subsidence due to two big Council Trees, in the big drought of 2018.
One tree was at 4.5 meters, the other was at 9 meters. 

I am on heavy clay soil. No maintenance done to  the Council Trees, which were planted with the Estate. They grew bigger and bigger! 

First signs were.....

-  cracks in the plaster above the bay window and above the internal door. 
-  That door and the outside door then starting to stick. (Eventually I could not open the outside door at all!)
- Then I returned from holiday in August 2018 to find zig-zag cracks on the outside corner near the trees and a separation of the bricklayer. 
- My concrete path along the side wall closest to the nearest tree also tilted....a lot. I really noticed the tilt when I walked along it. 

poorlittlefish

KJIWTIStructE said:

Mature trees close to houses also greatly increase the magnitude of volume change in the clay, making shallow foundations more prone to movement. 

Thanks, that's really helpful.  The bungalow was built in 2000 and from what I can see on the plans, its foundations are 750mm deep.  It's a timber-framed house, so although the outer walls are brick, they're not solid brick walls as such. 

I had four trees cut back about 3 months before the odd things started appearing in the house (the problems in the garden were already there).  The trees were on unregistered land next to my bungalow and, although fairly spindly in nature, they were about 80' high, so my concern was that they could fall on top of my home (I had made various enquiries as to ownership; conveniently the land all around the trees belongs to the council, but they claimed not to own the small patch the trees were on).  In cutting back trees to prevent one problem, could it have caused the one I'm now experiencing?