Loading...

STAIRS

Precast Stair Systems along with Stair and Elevator Shafts are an economical, quick solution for any new building. They are compatible with precast, steel, block or any type of building product. This product can speed up the construction schedule greatly by giving all trades access to all floors as soon as construction begins. No temporary access stairs or dangerous scaffolding is needed.

Advantages of Precast Stair Systems:

Precast Stair Systems can be installed at the beginning of the project eliminating the need for dangerous scaffolding and providing a safe way for subcontractors to access all levels of the building.

Precast Stair Systems are durable and very low maintenance.

Using Inventaa’s precast concrete flights and landings is by far the most efficient and professional method of building staircases in today’s modern method of construction.

Stair flights and landings are produced in the factory in controlled conditions in special mould designed and fabricated for this purpose. While the Staircases are being produced, site construction work can be done to prepare the building to receive them thus saving time and money. 

The advantages of using precast stairs are:

  • Unobstructed and safe access to the building during construction time. In situ casting of staircases will block the access for weeks at a time and the movement of the construction workers is hindered by the scaffolding. The staircases can also be erected simultaneous with Hollowcore slabs.
  • Turn key concept including design, manufacture, supply and   erection. 
  • High quality product with excellent concrete finish.
  • Time saving, reduced construction site costs. Using precast concrete stair cases will save both time and cost when site shuttering and scaffolding can be eliminated.
  • Precast stairs are fast and easy to install and can be utilized immediately after installation.
  • As all risers on flights are of exactly the same height, precast stairs are therefore much more comfortable to walk on compared to most stairs cast in situ.
  • All products have smooth surface finish with antislip coating and do not require any other finish layer like most cast in situ stairs.

Inventaa has three standard type systems depending upon your requirement and taste.
  
Stair type S1
This type is normally made with 2 flights, 1 intermediate landing and one main landing per floor, however it's also possible to combine the landing and flights in one unit. 

The height of the steps can be can be modified to suit all level heights.

Stair type S2
The S2 is constructed with 2 flight beams for each flight on which the step are mounted. Landing are supported directly on the flight beam extensions. This makes the whole system considerably lighter than the S1.

The height of the steps can be can be modified to suit all level heights.                 

Stair type S3
Our Newel stair is constructed step by step with a supporting column integrated in each step unit.
The finished result is a highly aesthetic staircase, light and elegant in appearance and require only little space.

The height of the steps can be can be modified to suit all level heights.

Staircases will normally be fair faced ready for paint and the step and landing plate surfaces can either be polished, fair faced or roughened.

Stair flights and landings are cast into purpose built moulds. Prior to casting, all cast in parts fixed in position and the mould is treated with a mould release agent. Hereafter reinforcement is kept in position and mould sides are fixed. All reinforcement will normally be prepared and prefabricated in our own workshop and placed in the mould using adequate spacers to ensure correct position and cover.

The specially manufactured casting equipment is employed to pour concrete into the moulds. The concrete used in production of these panels is manufactured under controlled conditions in our own batching and mixer plants employed specifically for captive use only. The in house production of concrete ensures highest possible quality. From batching plants, the concrete is transported directly to the casting equipment.

During casting hand held vibrators and fixed table vibrators are used to achieve the best possible compaction. The type of vibration, duration and amplitude of vibration is skilfully fixed based on pre-tests and type of element under casting.

After flights and landings are cast, they are covered with polythene sheets to avoid vaporization and left as it is to develop the initial strength. The concrete strength is ensured before the panels are removed from their mould and transported to curing and finishing area.

All precast panels are cured as per BS standard and company procedures. During the curing period, the panels are regularly watered and kept covered with polythene sheets to retail the moisture around panel.

Quality Control

Quality control is performed according to Inventaa standard quality procedures in the well-equipped laboratories. The testing equipment is calibrated and maintained at fixed intervals to ensure the test results are at par.

The material used in production of concrete undergoes inspection and testing as per company inspection procedures and Standards. The reinforcement steel used in the panels is as per Standards.  

Comprehensive strength of concrete is determined by standard test cubes from the fresh concrete. 

All moulds are individually checked before casting. The final product is checked and inspected to ensure it meets the required finish and is free from any snags.

All stair flights and landings are cured as per Standards and company procedures. During the curing period, the panels are regularly watered and kept covered with polythene sheets to retail the moisture around panel.

A full schedule of company standard quality control procedures can be requested from the Quality Department. As a special service, we can offer a full Quality Control Report for the individual project consisting of casting dates, cube test and other quality checks for the particular project. This service shall be agreed with our Sales Department.

Transportation and installation

Both flights and landings are normally transported on flat bed trailers and lifted directly from trailer into position.

In order to achieve the exact level required, each unit is placed on PVC or steel shims. The gap between the units and the structure on which it is resting will be filled with relative dry sand cement mortar.

Dowel holes with projecting steel will be grouted using a low shrink easy flow cement mix.

Design of stair cases is done considering the length of flights, step rises and application. When designing a stair case, the following proportions will be maintained in order to achieve a comfortable walk:

2* rise+ 1 going = 600

Recommended sizes for stairs:

Category

Rise

Going

Sum (g+2r)

Pitch

Clear width

Min 
(mm)

Max 
(mm)

Min 
(mm)

Max 
(mm)

Min 
(mm)

Max 
(mm)

Min 
(deg)

Max 
(mm)

Private stair

100

220

225

350

550

700

41.5

800

Public stair

100

190

250

350

550

700

38

1000

Assembly stair

100

180

280

350

550

700

33

1000

Strength:

Min. characteristics cube strength fcu=35 N/mm2

Cement:
OPC complying with the requirements

Water:
Clean water with total dissolved solid contents not exceeding 700ppm.

Coarse Aggregates:
Crushed aggregates complying with Standards.

Fine Aggregates:
All fine aggregates are sand complying with Standards.

Admixtures:
Water reducing admixtures complying with Standards.

Reinforcement:
All reinforcement steel complying with Standards.