Soil test analysis and piling

[3Cube 9]

I will just stress on the structural concept for your understanding.

Despite the various type of piles (ie: Bored, Micro, Reinforced Concrete, Bakau...), there will be pile caps to serve the purpose of cutting off pile & distribution of the building's dead & live loading. Dead load refers to non motion item such as the building itself, permanent fixtures, etc. Live load refers to everything else such as the occupant (human bodies), loose furnitures, etc. Such pile caps are usually design / sized as small surface (as in plan view) with higher height (as in side view)

In better soil / earth conditions, piles will be omitted but footing is a must. In this case footing are usually design / sized  as slightly larger (as compared to pile caps) in surface area but shallow height.

In my opinion, a professional D&B builder should have factored in the estimated cost (with slight adjustment after actual structural design of about say 5~15% of your total structural cost).  The slight adjustment I have to clarify is due to the difference in sizing of the footing during the estimation stage & the actual design stage.

As for other items such as soil investigation, etc. This should also be factored in by the contractor as it do not fluctuate a lot. Somewhere in the region of $3~5 grand for a residential.

In my previous completed job of a 2 storey with an attic & basement (ie: in layman terms, structurally 4 full plan view sized floors) The estimate during initial quotation was $343k strictly for structure excluding piles, soil testing, etc. in the end, after actual structural design & adding a lift structure (ordered by owner after completion of 2nd storey structure), The added cost are as follows:

1) Added design & submission fees (Engineer & Authorities) - $6k

2) Added structural element (entire building including lift added) - $34K

Of course there are other added cost due to the lift such as electrical, architectural adjustments. But for your understanding, we only focus on this thread's topic (ie: structure)  The lift equipment (ie: lift car, lift motor, etc) was paid separately by the owner.

So in this case, there was an increase of about 40 grand which is less than 12% from initial quote ($343K)

Another thing that I practice is always to include a separate contingency cost when preparing the initial quote. This will help offset any unforeseeable addition / adjustment the every job will face eventually. In my case it is usually about 10% of entire building cost including fees for architect, engineer, authority, etc

This way it soften the "blow" to the owner a contingency cost help to offset (in accounting).

 

[DaddyJP 1]

Hi 3Cube,

Very useful information. Thank you.

Could you share what is the land size and total buildup area of the project mentioned?

When was the project completed, pre covid?

If soil condition is good, still require raft or mat foundation?

How much of the cost $343k is due to the basement?

Thanks in advance.

 

[3Cube 9]

On 5/31/2021 at 6:21 PM, DaddyJP said:

Hi 3Cube,

Very useful information. Thank you.

Could you share what is the land size and total buildup area of the project mentioned?

When was the project completed, pre covid?

If soil condition is good, still require raft or mat foundation?

How much of the cost $343k is due to the basement?

Thanks in advance.

 

Land is located in Katong / Marine Parade area. Project TOP was in September 2015

Land sized is 3,232.4292 sqft. Gross Floor Area (GFA) is 4,546.7136 sqft (Total) of which part 795.67488 sqft is the basement. Bomb Shelter is in the basement.

Lift only serve 1st, 2nd & Attic Floors.

In all construction, Footing (for non-piliing) or Pilecap (for piles) is a must to provide structural stability to distribute the weight of the building & it's occupant onto the earth.

Estimate for the basement was $63K & the retaining walls was $43K, Pilecaps is separately priced at $13.5k

To note the cost for basement exclude the basement ceiling (ie: 1st storey) which is separately priced.

[3Cube 9]

4 minutes ago, 3Cube said:

Land is located in Katong / Marine Parade area. Project TOP was in September 2015

Land sized is 3,232.4292 sqft. Gross Floor Area (GFA) is 4,546.7136 sqft (Total) of which part 795.67488 sqft is the basement. Bomb Shelter is in the basement.

Lift only serve 1st, 2nd & Attic Floors.

In all construction, Footing (for non-piliing) or Pilecap (for piles) is a must to provide structural stability to distribute the weight of the building & it's occupant onto the earth.

Estimate for the basement was $63K & the retaining walls was $43K, Pilecaps is separately priced at $13.5k

To note the cost for basement exclude the basement ceiling (ie: 1st storey) which is separately priced.

Another thing to note for the low basement cost.

During initial proposal stage with no Profession Engineer on board, I noted the difference in land level between the owner's Land & his 3 neighbors (Left, Right & Rear). So when the owner decide to have a basement, I was able to propose the construction method where minimal excavation was needed & also avoid requirement for shoring work (which will cost an additional minimum estimation of $100K)

Hence, in relation to the existing Land Level, I only need to excavate 1.5 metres to form bottom of the basement. After completing the basement, earth / soil was imported to top up the basement's surrounding. This result in the same land level with the neighbors, which is also required by the authorities during the submission stage.

[DaddyJP 1]

Thanks 3Cube.

I thought the basement cost of $100,000 is already high. U added it could be higher... 😮.

[snoozee 98]

8 minutes ago, DaddyJP said:

Thanks 3Cube.

I thought the basement cost of $100,000 is already high. U added it could be higher... 😮.

When you need to excavate deep, a lot of costs goes into the ERSS/shoring of the soil to prevent collapses. I had to pay around 50k for ERSS to build my RC trench to protect the sewer line which is just under 3m deep and 9m long. So you can imagine how much more it would cost to do an ERSS for a much bigger area for a basement.

[3Cube 9]

8 hours ago, DaddyJP said:

Thanks 3Cube.

I thought the basement cost of $100,000 is already high. U added it could be higher... 😮.

This is reasonable cheap cost when you consider the rate only comes to $133.22 per sqft of basement structure. Ask around & you'll know. This includes everything for basement construction (ie: temporary minimal shoring 1.5 metres depth, excavation, topping up soil, concrete, waterproofing, steel reinforcement, etc) nly exclude asthetic architectural works like painting, tiling, etc

If by conventional full excavation like snoozee, this could balloon to more than twice when include sheet pile shoring & ERSS Consultant Fees. Not to mention a bigger working area is needed.

By the way, I also help owner to save on GST.

Basically, The entire project including Architect, Engineer, Clerk of Works, Authorites' fee, etc (exculding the lift equipment only) cost only less than $308 per sqft.

GST was not legally required as I did not take up other jobs so as to keep my company's revenue  below 1 million per financial year. This job's duration was spread over 3 financial years (Started design & submission end 2013, Complete TOP September 2015).

Why do I do this? You may ask...

My company is small so this will help in small way to compete with other firms. I personally double up as Architect (for design & drafting of plans) which means saving for Architect's fees (only paid minimum fee to Registered Architect for endorsement / submission)

All in all, I shave off at least $44 per sqft in cost for the owner

Edited June 3, 2021 by 3Cube
added information

[Alkft 0]

On 6/3/2021 at 9:03 AM, 3Cube said:

This is reasonable cheap cost when you consider the rate only comes to $133.22 per sqft of basement structure. Ask around & you'll know. This includes everything for basement construction (ie: temporary minimal shoring 1.5 metres depth, excavation, topping up soil, concrete, waterproofing, steel reinforcement, etc) nly exclude asthetic architectural works like painting, tiling, etc

If by conventional full excavation like snoozee, this could balloon to more than twice when include sheet pile shoring & ERSS Consultant Fees. Not to mention a bigger working area is needed.

By the way, I also help owner to save on GST.

Basically, The entire project including Architect, Engineer, Clerk of Works, Authorites' fee, etc (exculding the lift equipment only) cost only less than $308 per sqft.

GST was not legally required as I did not take up other jobs so as to keep my company's revenue  below 1 million per financial year. This job's duration was spread over 3 financial years (Started design & submission end 2013, Complete TOP September 2015).

Why do I do this? You may ask...

My company is small so this will help in small way to compete with other firms. I personally double up as Architect (for design & drafting of plans) which means saving for Architect's fees (only paid minimum fee to Registered Architect for endorsement / submission)

All in all, I shave off at least $44 per sqft in cost for the owner

Hi 3cube, May I ask is your company a design and build? 

Also wanted to ask if a soil test done for an interterrace to do rear extensions and perhaps to reposition a pillar at car porch front middle to the side, what will the process be like? 

Are the soil test done the same for varying types of housing? 

[3Cube 9]

On 6/6/2021 at 8:40 AM, Alkft said:

Hi 3cube, May I ask is your company a design and build? 

Also wanted to ask if a soil test done for an interterrace to do rear extensions and perhaps to reposition a pillar at car porch front middle to the side, what will the process be like? 

Are the soil test done the same for varying types of housing? 

First & foremost, I said in my previous post as follow:

"This job's duration was spread over 3 financial years (Started design & submission end 2013, Complete TOP September 2015)."

"I personally double up as Architect (for design & drafting of plans) which means saving for Architect's fees (only paid minimum fee to Registered Architect for endorsement / submission)"

This should answer your question.

Next, any form of works which extends a building's perimeter (ie: increase floor footage area) will involve structural works. It would be wise to conduct soil test. Just imagine. When you spend money to extend & add but do not consider foundation load bearing, you'll likely end up with a finished product which result in building defects ranging from sinking or leaking (from structural cracks) building (minor) to total building collapse (major).

Water leakage will be an issue. The best waterproofing in the world will not be 100% as you'll need some form of maintenance down the line after completion.

For your case or works at rear of you inter-terrace, added cost will be required to move in the machinery & make good affected element while moving in the machinery. Your existing headroom will be a problem as machinery ain't small. This cost will be substantial.

I'm giving my opinion based on worse case assumptions / scenario with no knowledge of your site's condition.

[rexxie 0]

Hi 3cube, thank you, enjoy your postings. Will you drop me a PM, your mail box is full? Need some advice from you. Thanks

[3Cube 9]

12 hours ago, rexxie said:

Hi 3cube, thank you, enjoy your postings. Will you drop me a PM, your mail box is full? Need some advice from you. Thanks

Just post on the thread & I'll answer to best of my knowledge / construction experience. Beside it'll be beneficial to share with all.

[SAINT007 0]

Removing the post from here and move as a new topic. 

Edited April 13, 2022 by SAINT007
REPOST AS NEW TOPIC