marsaday, hi.
A quick question? that is has the crack that was flagged in the two reports noted opened up again, if after this amount of time it could be regarded as being stable, if however the crack has opened then it is probable that there is on-going movement of the property.
As an aside the position of the crack, door on ground to first floor window all too common, several non Subsidence caused spring to mind, Lintel failure, Thermal and moisture movement of the wall being two.
If you are going to do a major make over then you could consider, provided the crack has NOT re-opened re-pointing the entire wall, this will have the effect of blending in the old crack, the insertion of Helibar across the crack will assist if a general re-point is considered.
As for traditional underpinning that you are contemplating, I have not seen that done for a long. long time, the last one failed because the inexperienced Developer / Builder removed a two to three meter length of fill under a massive wall and left it for a day prior to infill with Concrete.
When I go to a Subsidence insurance claim there are several protocols that happen.
1/. Instruct a Soils Investigation to a depth of about five meters in at least two locations, the results of this will give information not only on the various strata but also the bearing capacity of the soils at differing depths.
2/. instruct a drain survey to check for leaking drains, repair as required.
3/. in a few cases, now considered by insurers and Loss Adjusters as a waste of time, you can monitor the crack using studs or proprietary crack monitoring gauges.
4/. Depending on the type of Property instruct either Uretek or Shire piles to visit and design then get a cost for installation of either system, they will undertake the design work, obtain a building Control approval. The type of preferred method is dependant on a number of factors, for example, Uretek does not like Peat.
5/. Work starts and completes, building Control Certificate produced, Installers documentation forthcoming.
6/. Finally the insurer or more likely the loss Adjuster issues a Certificate of Structural Adequacy.
The above is an approximation of what tends to happen in an Insurance claim, as an aside Scotland is slightly different, well why not?
Now for the kicker, when you come to sell !
You will have to declare that there is Underpinning [of whatever type] to the prospective purchaser.
The prospective purchaser may be scared off instantly? or start to go through the process of purchase, the prospective purchaser Solicitor should pick up on the underpinning and may ask questions if the Solicitor for the purchased is on the ball.
Lets say the purchase is well advanced the prospective buyer starts to cast around looking for insurance.
If the Underpinning has been completed by an Insurance claim then there is a possibility, no greater than that, the next Insurer will consider the risk, but, there may be several exclusions as regards Subsidence, or the premiums will be higher than normal for this property in this area.
If you proceed and undertake a DIY underpinning, I think everyone will simply run and keep on going. what is your track record in underpinning? is the one question the underwriter will ask.
At one time if an insurer issued a Certificate of Structural Adequacy to the seller, if the purchaser applies to the same Insurer, and is deemed a good risk by that insurer then cover will [probably] be given, but not in all cases.
Insurance and such things are exceptionally complex issues, there are some rules, but and this is a big, big but no two Insurers will make the same decision as regards an event.
Ken