How to avoid rising damp in your building

While a  glass of cold water on a hot day maybe what the good doctor ordered, it’s also true that water can be a menace especially in building construction. In fact it is  common knowledge that water can be a source of headache because of a plethora of problems it can cause when it pops up uninvited in your building floors and walls.  Apart  from  posing a  great  personal health risk, it will  leave  your  floor with tiles  that lift and  wobble  as  well as  causing damage to the hardwood floor finishing  and  walls  that  sports  ugly finishing paint  blisters  and  mildews. To  ensure that you  don’t personally come  to acquaint your  esteemed self  with these  pesky  problems in your proposed   especial   building  you might want to  call  home ,here is  what  you  need to know: This  menace has solutions  that  work all the  time and revolve  around  high  water table and  capillary action of  water.

Building on high water table site   like a swamp require significant modification to the standard building construction design and work. Because  these  are  grounds  that receive  and retain excess  water  during  the  wet  seasons ,the  contractor, in the first place    must  drain the site  of all the water .Then you  want your house simply off   ground    which can be accomplished   either by  utilizing the ground  space a  garage  and  locating your living  area  rooms on first floor. This   should isolate your house from the damp ground.

Or you could use suspended concrete floors. A suspended concrete  floors is  supported  by  the external  and  internal  load bearing  walls  and is independent  of the  ground  beneath it. The Contractor will ideally use  Pre-cast  concrete  in the shape  and  form of  a series  of  Inverted   “T” beams  and concrete block  in fills. When the  beams  and  blocks are  craned  in place, a mix of   moist  cement/  sand  is  brushed  over the  surface   to fill the  gaps between  them. This  grout  helps   not only to distribute  the  load  across the  floor  and  prevent  future  movements  of the blocks but also it  helps  keep insects  and vermin out. Once the floor   receives a finishing work, you can rest assured it will remain dry the rest of it is useful life.

If  on the other hand   your building construction site has  a low water  table,  then you  have  to   look out  for  capillary action of water-that is  rising  damp  from  small  amount  of  moisture  from the   ground . Although this  can  develop into  a throbbing pain, its  easily  forestalled  by incorporating the damp proof  membrane(DPM)  on the  floor  during  construction. In other words before pouring the concrete slab, the Mason must a lay thick polythene sheet membrane over the blinding.  Since concrete  is  not  completely  waterproof  and  this  membrane  is an effective   barrier to  the  rising  damp  which  will  keep the floor surface  literally  home  and dry.

It  very  important  to  remember that the DPM must  overlap  the  DPC running  along the  walls to  ensure  that the  superstructure  is  kept  separate from the  substructure. This  way, no  moisture  can find its way up  to the  walls  and  floors  above  the  ground.

Other suitable damp proof membrane materials are bitumen and asphalt. Bitumen should be  applied   hot (when   it is  liquid)  and  about  3mm  thick  to a  clean  concrete  slab. Although it is   more  expensive  ,  it  however  offers the  best  protection against  rising moisture and  is  suitable for all  floor  finishes  like  cork tiles, Vinyl tiles or  pure  cement finish. Liquid Asphalt  is also , on the other hand    applied hot  and to  a thickness  of  about 20mm.It  can be  troweled  and  does  not  normally  required  a separate  screed; the finishing tiles  are  laid  directly  on it.

To finish off this capillary action of water menace, the Masons must incorporate a damp proof course (DPC) to all load bearing and non-load bearing walls. While load bearing wall requires a foundation   trenches the no-load bearing wall requires a thickening in the slab. However  in both  cases  a  damp proof  course   is  required    under the wall because overlapping    polythene  membrane   need reinforcement  along the wall  to  completely keep them   moisture-proof .It is   not a good idea to leave the DPC out  because it can  cause  minor  expansion  of the  blocks  that  can affect  the plaster  finish  occasioning un-slightly  paint   blisters and  poor  house  interior  conditions that  may  pose a health  hazard to the occupants.

©2017 Copyright: East Africa Little Hardware Ltd


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