When building a conservatory or orangery you will need an understanding
of the soil and ground conditions before any work can be undertaken on
the building foundations. Most conservatory or orangery companies do not
provide ground work as part of their service so ideally you should find
a company that does because the work can then be included within both
the cost and guarantee. Given all of that it is a good idea to have some
knowledge about how the ground conditions will affect your build, after
all, it is what your conservatory or orangery will sit on.
Before any building work can be started an understanding of the subsoil
strata will be required first. When doing this you will need to consider
the following:
• The position of sewers.
• The position of inspection covers for drains.
• Whether the soil is clay or not.
• Whether the site is on reclaimed land or not.
• How close trees are to the proposed building.
Building over or near sewers
If your house was built prior to 1939 then it should have a private
sewer system so it will not be owned by a local water authority. If
unsure then just contact your local authority to find out. If you are
building within 3 meters of a public sewer then legally you must contact
the local water authority and consult with them before gaining their
approval for the build. Allow time for this within your schedule. Also,
you need to know the position of existing pipe work to ensure the extra
weight cause no problems like cracks.
Building over inspection covers
If you plan to build over drainage inspection covers you really have two
options, build over it or move it. Building over it can be an easy
option but make your builders install a sealed screw down cover over the
existing cover to prevent odours and gases coming into your new
conservatory. This of course will affect your choice to flooring too. If
there are no other inspection covers it may be worth moving it to a
point where you can gain easy access. Remember blocked drains are not
common but over the life span of the property they can occur, so if they
do and your toilet facilities are overflowing, think how quickly and
easily you will want to fix this!
Building on clay soils
Clay soil is subject to big changes in volume due to the moisture it
carries. This volume change depends upon the make up of the fine
particles that make up clay. Foundations within clay soils need to be a
minimum of 1 meter but if the clay is very soft this may need to be
deeper. A good builder will consult the local authority building
inspector regarding this and this may need signed building regulations
before you can insure your property.
Building on reclaimed land
Britain has limited space, a need for homes and a rich industrial past.
All this means your property may be built on reclaimed land. This could
be a brown fill site or old marsh land. What this means is that your
conservatory or orangery may need different foundations to the standard
build. This is not arduous as it used to be and it is now quite common
to sink concrete bore holes into the ground so they rest of more solid
ground. These bore holes then have concrete beams placed between them to
provide a solid base. With access to the property and modern machinery
this is not as big a job as it used to be, in fact one can even hire
smaller bore hold diggers if access is restricted. That said it is still
more work than normal foundations so this needs to be factored in.
Building near trees
Trees can take up so much moisture from the soil that this can cause
subsidence. Therefore it is necessary to ensure you have the right
foundations to avoid this problem if you are building your conservatory
or orangery near trees. The guide is that if you are building within 35
meters then you could be affected. The type, the size and number of
trees will clearly have a big impact on this. To help with this, the
British Standard 5837 2005 “Guide for Trees in Relations to
Construction” will be very helpful.
As with all of these considerations, it is a good idea to seek good
advice on your particular build and it is a good idea to consider a
conservatory or orangery company that include ground-works within their
service so they can factor this into the build of your conservatory.
Understanding How Ground Conditions Affect Your Conservatory or Orangery Build
