# cost of: demolishing, clearing ground and digging for foundations



## housecat (23 Jan 2011)

Hi,

Thinking to save some cash with an extension project, I was wondering how much I could save by demolishing the old extension myself, then clearing the ground and digging for the foundations of the new extension, all before the main contractor comes.

*Maybe you have some idea on the cost of this if the builder was to do it instead? *Some detail:


Location: Dublin 14;
Site: Semi-D, Back of the house, minidigger possible, wheelbarrow for rubble;
Extension to be demolished: ground floor only, 4m x 3m (12 sqm or 130 sqf circa);
New extension: ground floor only, 40 sqm or 430 sqf circa, about 20 linear metres of foundation to be dig;
Thanks for any help!


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## onq (24 Jan 2011)

I don't know what you might save, but when asked by homeowners for a ball park for site clearance figure for insurance purposes I usually suggest €20K for a house clearance.
In the present case, the issue isn't solely what you will save, but what you stand to save if everything goes well vs what you risk losing if you make a mistake.

There is a lot more to preparing the site than site clearance, and much more still to preparing the ground for foundations that simply digging holes.


 All organic material has to be cleared not just the surface sod, but also the roots and rootlets under the ground and you have to bring in an engineer to design foundations if you hit "made" ground - i.e. backfilled with soil, debris or rubbish etc.
 To aoid differential settlement the ground and water table must be assessed competently and any soft spots tamped down and filled and again, foundations should be designed by an engineer if bridging is required.
 In relation to clearing the superstructure, you have to proceed with caution, bracing before proceeding and properly assessing the existing structure for stress concentrations before you do anything.
 There are many ways to approach the work and not all will yield comparable good results across the board depending on the construction. Pinning rear walls to alow placement of steel supports, for example, is specialist building work.
     None of the above IMO should be attempted by a layperson, but the Health and Safety regulations seem to shy away from work on private residences being done by the owner.

My best advice is to leave it to the experts, because your trying to save on an area of construction which, if you make mistakes, could cost you significantly in terms of your finances, damage to the existing property, problems with the new work and your own health if you have an accident - even assuming you can get the insurance, it can cost you dearly.

There is an old adage in the building industry - stick to what you're good at.
Don't attempt this work for the first time on your own sole domicile.

If you're determined to proceed please read the requirements for safety gear and good practice on the Health and Safety website.
Familiarize yourself with the conditions and risks associated with working on insecure footing, in cold weather, wearing safety equipment.
If you are in a sedentary occupation and don't exercise much, you should undergo a programme of fitness, stamina and strength development.

If you don't prepare your body for the heavy manual work involved [mini-digger regardless] and allow for sufficient rest and nutrition, you can break your health.
As a bare minimum of preparation you should attend at a Safe Pass Course for site work [general operative] and attain the pass - its usually one day and well worth it.
If you intend to engage in using a mini-digger and/or demolition work, or working near services or on a height, you should attend Safe Pass Courses for these activities also.

Take on board this non-exhaustive list of warnings as an absolute minimum.

- *GET TRAINED* - you are not a site operative and you need to be briefed on the dangers.

- *DEAL WITH SERVICES COMPETENTLY* - map and neutralise existing services - electricy, gas, water - call in the experts.

- *WEAR PROTECTIVE EQUIPMENT* - Gloves, Helmets, Boots, Hi- Viz Vest, Face Protector - you are not Superman - you can be damaged.

- *WEAR PROPER CLOTHING* - no loose clothing to catch on projections or machinery eg. getting an angle-grinder in the face because of a "hoodie" string.

- *PROTECT YOUR FAMILY AND FRIENDS* - a site is not a playground for children and demolitions or excavation work can affect a whole building - while people are in it.

- *DO NOT WORK ALONE* - accidents happen and having someone nearby should you be injured can make all the difference between surviving, surviving whole, and not surviving at all.

- *PREPARE THE WORK PROPERLY* - do not carry out demolitions or excavations without propping to best practice standards - you may end up injured or worse and you may do significant damage.

- *TAKE PHOTOGRAPHS OF YOUR WORK* -  do not cover up any or the diggings with lean mix or a sand layer - an engineer or the contractor will need to properly assess the ground.


This isn't exhaustive advice, and by just reading down the list you can see the risk you're running by doing building work yourself.

HTH

ONQ.

[broken link removed]

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## BICIP (24 Jan 2011)

Unless you're experienced in ground works I'd say leave it to the builder.


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## housecat (24 Jan 2011)

Thank you for the informative reply ONQ (!) While I have yet to tender for the whole project (as I will) I really remain very interested to hear about the cost for *demolishing, clearing ground and digging for foundations* that some other similar-size job has been quoted for. Thanks in advance for any information. HC


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## Docarch (24 Jan 2011)

I was just looking at a tender/rates recieved from a contractor for a not dis-similar sized job in Dublin and I reckon you may save approx. E4.5k on the demolition and clearance and maybe E2k on the excavation for foundations (assuming they are standard strip foundations). 

I hope that may somewhat satisfy your curiosity?  I will not go into anymore detail than that as of course the devil is in the detail and I do not want to mis-lead! 

I would suggest of course you are better off getting the building contractor to do the whole lot (and I would support/echo what ONQ has stated above).

As you suggest yourself, price the whole job (but ask for a full breakdown from contractors when they submit their price) and then if the overall price is too much, discuss with the selected or preferred contractor the option of taking on the demolition and excavation yourself and how much you might save. Without engageing a quantity surveyor yourself, this is the only real way you will get an idea of the actual cost for your particular situation.


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## housecat (26 Jan 2011)

Thank you again!


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