Why You Should Avoid The Use of Spiral Staircase as Emergency Exit - Osaz’ ENOBAKHARE

Emergency exit in buildings is essentially designed for quick escape from hazards like fire and other forms of attack. When there are exigencies of such nature, the use of escape routes comes to bear. The positioning and allowance of escape media should be such that nothing is taken for granted. It is not uncommon to see spiral stairs of metal, concrete or composite type installed in position of emergency exits in buildings across the country but research and common sense shows that this form of exit is not very effective in times of emergency.

The use of spiral stairs as exit media is not exactly a bad idea but its use as an emergency exit especially in assembly buildings like worship centres and halls or other building types with high occupancy ratio like hotels, multi-storey residential/commercial buildings or condominiums is where the problem lies. 

The rush of a crowd in an emergency situation can be further hampered by attempts by individuals to make sharp angular turns at close distances between steps on a spiral stairs. The intense pressure and panic associated with an attempt to escape coupled with the range, size or rate of spread of the attack might cause intending escapees to get stuck at the exit area.  


It is fact that the use of spiral staircase as emergency exit poses another form of danger to those who must have assuredly relied on it as an escape route hence some states in Nigeria (e.g. Lagos) have frowned at it.

Consider this simple scenario -a couple of people trying to escape an electric fire attack from an upper floor say a regular 3-floor height, each person may have to make at least 9 sharp turns joggling down from riser to riser before they can alight at the ground floor. 

Spiral Staircase (Dangerous for emergencies)

The issue then is with each person trying to outrun the other within a small stair-width and considering the angle of turn and the steepness of typical spiral stairs, there is a higher tendency for the occurrence of multiple somersaults which may cause serious injuries and even instant death. Sometimes because of the height and mode of fall and perhaps the degree of injury sustained during the fall, such victims of somersault or associated stampede may have to contend with a duo challenge on their hands –that is getting enough strength to get up from their landing position and then the original burden of completing their escape episode. 

This action could be dramatically horrible and have accounted for quantum loss of lives in past and recent building fire-outbreak scenarios. This is not to say that such cases of falling off are only peculiar to spiral staircases –No! Fear, panic and ‘adrenaline action’ can make people escaping from an attack via a straight-flight staircase fall-off like ‘they don’t care’ but it is very likely that if the same number of unsuspecting victims, under the same condition of attack use a spiral staircase as emergency, there would be higher casualty.

Although most building owners especially those mindful of what is often described as ‘maximal use of space for increased value’ are reluctant to allow greater space for the installation of decent emergency exit(s) and would rather prefer any staircase that can squeeze itself into a small area, the use of spiral stairs especially the typical metal variant is not ideal and no longer in vogue. 

Large Helical Staircase on a high-rise Office Building

But for developers or building owners with this sort of mindset and where building regulations do not restrict, there is a way out and that is the use of helical stairs. Helical stairs are different from spiral staircases in elevation and take up spaces slightly larger than that their counterpart.            

It has been observed that where new building regulations forbid the use of typical spiral staircases as emergency exit, some developers have added more spaces to accommodate the replacement of their spiral staircases with helical stairs. 

RC Helical Staircase (for Emergency Exit)
 constructed by Heavens at Ibis Hotel Ikeja, Lagos, 2016

These stairs also allows for turnings but such turns are not as sharp as those of typical spiral stairs and are generally safer. Half-turn and straight-flight stairs are amongst the best options for emergency exits. It is therefore advisable that at a time when building fire incidences have become prevalent, developers and building owners especially of assembly and high density buildings begin to think aloud and do the needful.

Uncommon, Efficient Method of Producing Sets of Terraces Houses Within Four Weeks - Osaz’ ENOBAKHARE

It starts with the design. Do or get a simple but ‘stand-out’ design that can easily be interpreted; Complex designs with too many chaffer, projection, bend, twist and curves may reduce construction speed. Terrace houses are mostly proto-type and are often arranged in simple rows sharing the same roof, partitions and sometimes the same longitudinal bearing in foundation making it easier to construct than a typical set of detached buildings. 

Typical terrace consists of 10 units or less, although there is really no limit. The main partition between individual units can be extended to form a fence to enhance security and privacy. By adopting the right construction technology/technique, project cash flow pattern and employing a versatile contractor, a four-week project duration for a row of terrace houses can be achieved as shown in these simple steps;

Day 1: Mobilize plants, address the workmen and call up suppliers. It is often good to notify your workmen and suppliers a fortnight to the start of site work so that you can determine their availability or level of preparedness. As early as possible, they are assembled and given specific and general instruction. Distribute workmen into teams or gangs depending on their skill sets and roles. Duplication of roles should be avoided as much as possible. 

Day 2: Prepare the site. Clear and cart away debris. Begin to receive and store building materials as ordered. Deploy sufficient labor and material for the work at every material time and always pay prompt to avoid dispute. 

Day 3-7: Do your setting-out operation. Mark-out the entire row at once and begin foundation works simultaneously. Level and compact filling materials intensely. Substructure works may take up to 3 more days to complete. For concrete works, the norm is that it requires at least 21 days to set properly. Ask the in-tune professionals, this now depends largely on the constructor’s knowledge of new techniques that makes concrete achieve sufficient strength within a very short time using the right mix. Leave the entire foundation set-up undisturbed for a day –say the seventh day. Start construction of pre-cast components like floor/roof beams, lintel beams, inspection chamber, septic tank/soak-away pit, base for water treatment plant, etc.

Day 8 - 15: Begin super-structure works. Set up quick-fit scaffolds and small-sized hoist to lift up pre-cast members. Stack bricks or lay blocks depending on which wall material you are using and do your frame work (i.e. build columns, install beams, construct floors and staircases) alongside. For reinforced concrete in columns and beams use the same approach used in foundation. But for the upper floor, allow additional time before you detach the formwork because it is a suspended member with a larger horizontal surface area. Begin to cut the roof members into sizes ahead of installation. Start electrical, plumbing work and external work.

Day 16 – 20: Install your roof and ceiling members. Install fittings and fixtures. Render walls and floors.

Day 21 – 27: Install floor, walls and ceiling finishes. Perfect all finishes and external works. Do your checks and balances. 

Day 28: Close the project.

Looks too good to be true? It’s not an experiment. There are existing buildings delivered this way. Wouldn’t it just collapse? Far from it; they are just as structurally stable and durable. Collapses aren’t often caused by construction speed but incompetence and corner cutting. Or you thinking -why the rush? That’s probably the wrong question. In the footsteps of modern day constructors and with the prevalent high cost of servicing project loans, the right question is why all the unnecessary and avoidable delays?  It really depends on you.

Stop water from seeping into your buildings before it finally stops you - Osaz’ ENOBAKHARE

Beautiful structures with ground water seeping profusely into the ground floors and walls from the earth are like beautiful ladies suffering from acute bacterial infections; they may look good outside but inside, it’s a whole different condition. Have you lived in a house where floor/wall dampness or water wakes you up in the morning and embarrasses you before your visitors in the evening? You would probably understand that water can be a serious problem when it finds its way into the wrong places. 

Enter some buildings and you would feel the dampness even from your simple sense of smell –very unpleasant. Ground Water/moisture has been observed to flow against gravity when it seeps through open pores in the earth up into voids and very tiny air spaces in the foundation elements and then into the interior of the building in an action known as capillarity. 
Although this great ability of water/moisture can be effectively developed into new technologies for cooling buildings naturally during hot weather conditions, however uncontrolled movement of water/moisture in and around a building often end in a big mess.

Poor water control into a building from the ground can cause foundation failure over time. Little by little, secretly and later openly, the foundation begins to deteriorate rapidly with cracks surfacing and then collapse eventually if left unattended to. But there are a number of solutions to avert such ugly incidence; each depends on the peculiarity of the situation. 

Most foundation footings and ground floor slabs in Nigeria are made of concrete. It has been observed that as concrete dries and set during construction, it normally leaves tiny pores which winks in moisture from the earth and transport them upward to the surface. Hence a permanent solution lies in the use of damp-proof materials like bituminous felt, polyurethane membranes, nano-technology penetrants, crystalline sheets, plastic sheets, epoxy or a combination of any of them to cover the surface or contact point of the concrete exposed to the ground at the bottom or by the sides so that moisture would have no direct contact with the element at any point in time.

Before installing any damp-proof material to stop water ingress into the building’s interior, it is important to study the water flow pressure under and around the sub-structure. It won’t be sensible for instance to use bituminous felt where the flow pressure of moisture is relatively high. Once you do that, initially it stops the flow but in a matter of years, the moisture soaks and tear-up the felt, then the threat resumes again. 

Epoxy, crystalline and acrylic coatings are particularly useful where the moisture does not contain much salt and in low or moderate capillarity flow; else the salt begins to break the coating and over-staying water between the layer of the covering material and the earth weakens the material giving rise to leakages. But good quality polyurethane and plastic sheets are very suitable for use under any flow condition, anywhere in the country. They can last for the active life span of the building without much distortion.

However It is important to note that no matter how effective a damp-proofing material is, if not properly installed, the result may be worst than before the intervention; hence the service of an expert is highly recommended especially where a correction or renovation work is to be carried out.

Is it Structurally and Economically Efficient To Use Short Bored Piles For Perimeter Fencing In Swampy Areas? -Osaz’ ENOBAKHARE

Perimeter fence constructed on short-bored piles by Heavens at Isheri-North, Lagos, 2016.

It makes more economic sense to use short bored piles for perimeter fencing in swampy areas than to use raft or deep strip foundation which is in common use, it has been observed. However it is important to do it the right way. 

Generally, perimeter fence consists of non-load bearing walls or partially load-bearing walls depending on its use and configuration; hence the use of short bored piles is structurally permissible. By constructing reinforced concrete piles with adequate spacing, usually not more than 6m apart and capping them together longitudinally, fence walls of up to 4m can be built directly over the cap (or longitudinal bearing) saving the volume of concrete by up to 50%. Apart from being economical to use short bored piles capped together, it is equally structurally efficient.

Short bored piles are so called because they are constructed by boring the ground and then filling with reinforced concrete or mass concrete and they normally do not exceed 5-metres in depth.  They are relatively easier and quicker to construct unlike the longer ones. Once the depth of suitable soil strata is established, rather than constructing raft  or strip which consumes cost associated with trench excavation, formwork consisting of several boards lapped together with a lot of bracing as well as heavy reinforcement accompanying the concrete in foundation which is the common practice, it is faster and cheaper to use short bored piles.

Once the fencing layer is filled, prepared and the boring points are marked, the boring is done simultaneously with the insertion of the reinforcing steel piles (usually no casing is required) and concrete in an operation that may not usually do not last more than 30 minutes per point depending on the nature of the soil beneath. When the piles are set, a network of steel reinforcement is used to cap the starter bars of all the piles together. 

The set up is cast in concrete and is now set to receive the blocks or bricks for the fence. Presently, it cost an average of 10,000 NGN (depending on the area) to bore and fill a point. Hence for a 36m length which could be one face of a standard plot, only about 7 points is required and the volume of concrete is therefore minimal.  

With the cost per cubic metre of concrete still hovering around 30,000 NGN, it is more than logical to conclude that short bored pile foundation for perimeter fencing in swampy or water-logged areas is the way to go especially for large areas like residential estates, industrial complexes, etc

PADDED B.O.Q: The Highest Bid May Not Necesarily Be The Best - Osaz’ ENOBAKHARE

Some contractors are experts in the art of padding project cost estimates or priced bill of quantities to the detriment of their unsuspecting clients in the same way the trending subject of national discourse bordering on the ‘padded budget’. Padding an estimate even for a non-statutory project to satisfy whatever selfish aim is not only immoral but is treated in some climes as ‘criminal’. Having studied a couple of priced bills for construction projects in the past few months, I realized that ‘B.O.Q padding has got an old face’ and has some professional clients also in its victims’ list.

Let me take you through some of the tricks that unscrupulous contractors and their quantity surveyors (QS) use to defraud private project owners so you can detect them; 

¹They spike up provisional sums. Provisional sum is an amount allocated to a specialized service for which details are not yet available as at the time of tender. Allow for the provisional sum of ‘so so amount’ to be used for ‘so so service’ or to be paid to ‘so so expert’ for ‘so so service’. Traditionally it doesn’t have any rate or unit attached to it and so it may be very difficult to measure the extent of work to be done not to talk of the most reasonable amount to pay for such services but it is important that you ask your contractor/QS to furnish you with some details on the provisional sum, he may become jittery and then you can beat it down. If a provisional sum is to be made for fittings and fixtures for example, you have the right to know what kind of fittings and fixtures is to be installed and how much they cost. Some bills have provisional sums in tens of millions for works that can be done with a little over a Million Naira.

² They add frivolous items like 'Special' Professional fees. Sometimes one wonders why professional fees should be charged separately in a bill where the contractor’s overheads and profit have already been computed into all the rates. What then is the rationale behind such item, If not for padding sake? Professional fees are only charged separately as an item if it has not been computed into the rates. Once you spot out such item in your bill, do not hesitate to ask questions.

³They keep reasonable rates but increase the quantities. Hardly is there a project owner who would go take a ground measurement by him/herself or measure quantities from a drawing for a new project because it’s a different ball game altogether as it requires some special skills hence undue advantage is often taken in this regard. The idea is to make the rates appear very normal so that much attention is not given to the quantities or volume of the items of work. You see quantities like 685sqM for floor tiles of a bungalow to be built on half-plot when the entire floor size of the land is below 350sqM. It really doesn’t make sense. When it is multiplied by the rate it increases the final amount. So take your time to study the quantities too as much as you would do with the rates and amount. If you discover anything suspicious, draw the estimator’s attention to it.

⁴ They repeat the same item using several titles/descriptions. Haven’t you seen two separate provisions for concrete/reinforcement in column and concrete/reinforcement in pillar in the same bill? One wonders what the difference is between 'pillar' and 'column'. Sometimes you see separate provisions for wall rendering and plastering when they are both nearest in meaning. Some insert separate provisions for flooring and screeded bed to receive tiles and so on.

⁵ They do guess estimate.  This is common in practice. They insert figures into the bill by relying on guess work and unfounded assumptions rather than current market realities just to arrive at a figure that they already have in mind. There have been reports that some of them use fetish means to sway/cajole their victims. On a recent project, a piling work that cost only about 8.8 Million Naira (overhead and profit inclusive) to complete was quoted by another contractor at a whooping 17 Million Naira. If the project owner had not contacted me on time, he would have donated 8.2 Million Naira free money to a ‘good guesser’.

Owner’s Interest Versus Standard Practice: When To Say ‘NO’ - Osaz’ ENOBAKHARE

Yes, it is true that the Customer is always King, however kings also live by standards; no sane king would allow his throne to be desecrated with thrash and garbage. In practice, there is often the desire to constantly satisfy the requirements and expectations of a project owner but it is also good to do this with some caution. There are well documented minimum architectural and engineering standards that guide the design and construction of buildings and other associated infrastructure which should be strictly adhered to. They are set at minimum so as to allow for some degree of flexibility in the use of discretion to play above them but definitely not to go below.  However it has been observed that some constructors even in collusion with their Clients deliberately pretend they don’t know it matters; putting the lives and properties of the future users or occupiers of such facilities in danger. Let’s take common case scenarios;

Some project owners are fond of requesting that their designers or architects produce two sets of drawings; one to be submitted for approval while the other set is to be actually built. Most times the later sets of drawings fall below currently acceptable minimum design standard. Some of these buildings do not meet basic access, ventilation and spacing requirements. Once completed, future occupiers of such buildings may have to suffer from poor air circulation even in the midst of plenty air or poor allowance for escape from fire, etc. Owners of such properties may have compelled the designers to deliberately manipulate the later set of building design to satisfy some selfish economic interests at the expense of the health and life of the future occupiers. Some others who are even seen to be working with the approved design still prevail on the constructor during construction to manipulate it against the requirement of the building code inasmuch as it is to their benefit, especially if the building is developed for investment purpose.    

Similarly, some others abuse the quantities or sizes of aggregates and mix ratios. It is established in basic engineering code that the larger the aggregates (or granite) used to produce a concrete the stronger the concrete product, therefore it is completely absurd to use stone dust or quarter-inch granite in the common mix ratio to construct load bearing elements like foundations, suspended floors, columns and beams especially in single and multi-storey buildings. But there are ongoing projects where this sort of awkward activity is done with so much impunity even under the watchful eye of the project owner. Sometimes the excuse is that such aggregates are cheaper and voluminous thereby helping to save overall construction cost but saving cost at the expense of lives is obviously not the way to go.

There are many of such ugly acts which cannot be captured in a single article but the crux of the matter is that contractors should learn to avoid undue influence from their client and insist on doing the right thing especially in critical processes.

How To Construct Swimming Pool On Upper Floors: Not As Difficult As You Thought -Osaz’ ENOBAKHARE

Modern building designs are placing swimming pools on upper floors in hotels, office towers, leisure parks, resorts and even private homes. The Nigerian real estate industry is not an exemption. The quest for creativity and luxury by project owners, especially those with a good degree of international exposure is pushing indigenous architects, builders and engineers out of their comfort zone. 

Renovation experts seeking to completely transform the spaces in a multi-floor building can apply the wonders of upper/suspended swimming pools. 

Adequately-sized swimming pools can be constructed into family living rooms on upper floors in multi-dwelling units or terraces where a common/open ground pool do not promote a sense of privacy. ‘Swimming in the sky’ or ‘Swimming in the air’ –type upper pools are major selling points for luxury apartments and hotels the world over.

Here are helpful tips when considering the construction of a suspended pool;

-          Like every other suspended building member/component, there should be an accurate and detailed design that sizes the pool, maximizes its aesthetics and takes care of the head-room beneath the pool floor as well as maintainability. Likewise there is need for a structural engineering design that takes cognizance of the basic functional requirements of swimming pools which include strength, stability, durability, resistance to all internal and external forces, water pressure, vibrations and stresses in relation to the foundation support. Details of water flow pressure and pattern can be obtained from a water engineering analysis carried out by a water engineer for that purpose.

-          Whether cantilevered or simply supported, ensure that the floor beams constructed to support the pool are properly connected to the structural support frame of the building. Where possible, connect the pool decks to these pool beams too because the pool decks normally carry highly concentrated load. The pool beams must be able to sustain the load of the swimming pool at full capacity.

-          Whether pre-cast or cast in-situ, the pool floor should sit properly on the pool beams to promote structural balance.

-         

Damp proofing should be done on both the internal and external parts of the pool to sufficiently control movement of moisture/water.  

-          An effective system must be installed on the pool to enable pool water not to rise beyond a certain level so as not to spill out.

-          The water pressure pipes should be built in such a way that movement of water flow and suction does not impede on the stability of the structural set-up.

-          A light removable cover or barrier should be installed to prevent under-aged children from falling into the pool when not in use. 

World Highest-Placed Upper Floor Swimming Pool
on 118th floor in Ritz Carlton, Hong Kong.

     

     Constructing pools on upper floors is seen by some professionals as one heck of a task, but it isn’t after all.  The only big deal is that it doesn’t allow for guess work and it cost more when compared to doing a ground pool. Adding an upper pool to that building makes it exceptionally attractive, luxurious and increases its market value. Think about that!