how do i know what type of soil my houseis built on?

If it is light brown and sticky it's clay with a high P.H. (Alkaline), if it is dark brown and you can feel the sand in it it's light with a low P.H. (Acid). With pieces of chalk as on chalk hills it's Alkaline, on peat it will be Acid. Soils which have been cultivated over many years can be in between. Hope this helps you.

No idea where you live,D, but if you have a local agricultural college then they will be able to tell you exactly what soil is at your postcode. Or, more correctly, what yhe native soil type is; if it has been gardened for many years then it will have been improved.

to get a rough idea have a look in the local gardens. if there are lots of rhododendrons growing then you are acidic. very basic but a good rule of thumb.