Step 14
A Concealed-Blind Project, End to End
This capstone runs a single project through the whole discipline — a Cape Town office refurbishment with a continuous north-facing curtain-wall, a boardroom requiring blackout for AV, and a hotel-style suite with bedside control. We walk the decision chain: concept (flush ceiling pocket to keep the slab soffit reading clean), coordination (negotiating the 140 mm pocket against the sprinkler grid and the linear diffuser), fabric (3% OF screen on the open office, dim-out with side channels in the boardroom, blockout cavity blind in the inaccessible high-level clerestory), motorisation (mains tubular on a fused spur, RF group control, BMS override for the XA-driven daytime solar strategy), and specification (the schedule, the access fascia, the torque submittal).
Detailing checklist
- Run the full chain on each space: concept, coordination, fabric, motor, spec
- Record where the detail held and where budget/coordination forced a documented compromise
- Hand over an as-built O&M set: dimensions, dye lots, torques, access and warranty
Self-assessment
Assessment Question Bank (10 MCQs)
Application-based questions. Minimum pass mark 70% (7 of 10). Reveal each answer to check your reasoning and the section it draws on.
Question 1
An architect specifies a flush ceiling pocket sized at exactly 100 mm clear internal depth, dimensioned to a 45 mm tube. On a 2 700 mm drop of dim-out fabric the installation fails — the blind jams before fully retracting. What was the specification error?
AThe pocket was sized to the empty tube, not to the fully-rolled fabric diameter plus clearance
BThe 45 mm tube is too small for a 2 700 mm drop and should have been 32 mm
CDim-out fabric cannot be used in a flush ceiling pocket under any circumstances
DThe pocket should have been sized to the slot width, not the internal depth
Show answer & explanation
Correct: A. Lecture 2 sets the cardinal rule: size the pocket to the fully-rolled fabric diameter plus clearance, never to the empty tube. A long drop of thick dim-out fabric can roll to 95–110 mm, so a 100 mm pocket dimensioned to the bare 45 mm tube has no room for the rolled fabric. Smaller tubes (B) reduce capacity, not increase it; dim-out is usable with correct depth (C); slot width governs the fabric pass-through, not the roll capacity (D).
Question 2
A boardroom AV wall requires a concealed roller blind with no daylight intrusion. The standard roller runs about 18 mm narrower than the opening on each side. Which detail correctly eliminates the resulting defect?
ASpecifying a wider, more expensive fabric to fill the full opening width
BSide light-blocking channels (recessed U-channel or F-channel) with fabric-to-reveal overlap
CIncreasing the pocket depth so the rolled fabric sits higher in the void
DAdding a second blind behind the first to cover the side gaps
Show answer & explanation
Correct: B. Lecture 4 quantifies the side-gap light leak (15–20 mm each side) and specifies the remedy: side light-blocking channels (F-channel or recessed U-channel) plus fabric-to-reveal overlap and pocket-throat shadowing. Fabric does not run full opening width because brackets need clearance (A is impractical and still leaves end gaps); pocket depth (C) affects roll capacity, not side leak; a second blind (D) doubles cost and gaps.
Question 3
Under SANS 10400-XA:2021, an architect wants to claim a concealed internal blind as the primary means of controlling summer solar heat gain on a large north-facing glazed facade. What is the technically correct professional position?
AInternal blinds are the strongest solar-control lever and should always be the primary measure
BInternal shading is excluded entirely from any XA or SANS 204 calculation
CExternal shading intercepts solar energy before the glass and is the stronger lever; the internal blind's real but lesser contribution must be honestly documented in the rational design
DConcealment automatically improves the SHGC, so a concealed internal blind outperforms an exposed external one
Show answer & explanation
Correct: C. Lecture 11 sets the hierarchy under SANS 10400-XA:2021 and SANS 204: external shading intercepts solar energy before the glass and is the strongest lever, while an internal blind absorbs energy that has already entered and re-radiates part of it. The honest specifier claims the internal blind's real contribution and documents it in the rational-design submission. Internal is not the strongest (A); it does contribute and is not wholly excluded (B); concealment is aesthetic, not thermal (D).
Question 4
A 4 200 mm wide opening must be shaded by a concealed blind on a single 45 mm tube. The installer warns of fabric tracking and light leak. What is the correct response grounded in deflection coordination?
AProceed — a 45 mm tube spans any width if the motor torque is increased
BThe span exceeds the practical limit (~3 000–3 500 mm for a 45 mm tube); introduce an intermediate support, a larger tube, or split into coupled blinds
CSpecify a heavier fabric to weigh the tube down and prevent deflection
DMove the brackets inward so the tube spans only 3 000 mm and accept the side gaps
Show answer & explanation
Correct: B. Lecture 8 gives the span guidance: most 45 mm tubes are limited to roughly 3 000–3 500 mm before tube deflection causes fabric tracking and light leak; beyond that, use an intermediate support, a larger tube, or split into coupled blinds (Lecture 9). Torque (A) drives the motor, not deflection; heavier fabric (C) increases load and deflection; moving brackets inward (D) creates unshaded side gaps.
Question 5
A continuous concealed-blind ceiling pocket runs across a line where a compartment wall meets the soffit. The fire engineer flags the detail. Which standard governs the required remedy, and what is it?
ASANS 10400-XA — the pocket must be insulated to limit heat loss
BSANS 10400-O — the pocket must not reduce daylight below the minimum
CSANS 10400-T — cavity barriers must maintain compartmentation where the void crosses the compartment line, and the blind detail must not defeat them
DSANS 204 — the pocket must meet the building's energy budget
Show answer & explanation
Correct: C. Lecture 12 identifies SANS 10400-T (fire protection) as governing: a continuous ceiling void crossing a compartment line is a smoke and fire path, so cavity barriers must maintain compartmentation and the concealed-blind detail must not defeat them. XA (A) is energy, O (B) is daylight/ventilation, 204 (D) is energy efficiency — none address compartmentation.
Question 6
A client questions why a 'concealed blind' on the curtain-wall costs more to specify than a face-fixed roller. The architect's best technical justification is that:
AConcealment is purely aesthetic and adds no functional value, so the cost is discretionary
BConcealment is a coordinated detail spanning ceiling, structure, electrical, fire and access trades — it is detailing, not a product, and the cost reflects that coordination
CConcealed blinds use fundamentally different motors that are inherently more expensive
DThe fabric in a concealed blind must always be blockout, which costs more
Show answer & explanation
Correct: B. Lecture 1 frames the discipline: concealment is not a product but a coordinated detail involving the ceiling, window head, structure and three or four trades. Lectures 3, 6, 8 and 12 develop the ceiling, electrical, structural and fire coordination. The cost reflects coordination, not a single component. Concealment has real functional/aesthetic value (A); motors are sized to the blind regardless of concealment (C); fabric choice is open (D).
Question 7
Which powered-blind safety and product standards should an architect cite when specifying a motorised concealed internal blind for a South African commercial project?
ASANS 10400-A for general principles and SANS 1186 for fasteners only
BSANS/IEC 60335-2-97 for the safety of powered blinds/shutters and EN 13120 for internal blind safety and performance
CSANS 204 for energy and SANS 10400-S for accessibility only
DEN 17037 for daylight and EN 14501 for glare classes only
Show answer & explanation
Correct: B. Lecture 6 names SANS/IEC 60335-2-97 (safety of motor-operated blinds, shutters, awnings) and EN 13120 (internal blinds — performance and safety) as the governing standards for a motorised internal blind. The other options name real but unrelated standards: A covers fasteners, C covers energy/accessibility, D covers daylight/glare — none are the powered-blind safety standards.
Question 8
An architect must choose between a between-glass cavity blind and a ceiling-pocket blind for a high-level inaccessible clerestory above a double-height atrium. Which choice and reasoning is correct?
ACeiling-pocket blind, because cavity blinds cannot be motorised
BCavity blind, because it is sealed, dust-free and maintenance-free for the unit's life — appropriate where maintenance access is impossible, accepting that a failure means replacing the glazing unit
CCeiling-pocket blind, because cavity blinds offer no thermal benefit
DCavity blind, because it is always cheaper than a ceiling-pocket blind
Show answer & explanation
Correct: B. Lecture 10 sets the decision matrix: cavity (between-glass) blinds are sealed, dust-free and maintenance-free, making them the right call for inaccessible, high-level glazing where maintenance access is impossible — with the caveat that a failed cavity blind means a replaced glazing unit. Cavity blinds can be motor/magnet driven (A wrong); they do affect solar heat gain (C wrong); they are generally not cheaper (D wrong).
Question 9
When sizing a tubular motor for a tall, heavy concealed dim-out blind, an architect reviews the manufacturer's torque submittal. The motor is rated 6 Nm; the calculated requirement is 9 Nm. The blind is in a sealed flush pocket. What is the correct action?
AAccept it — torque ratings include a large hidden safety margin, so 6 Nm will be adequate
BReject the submittal and require a motor whose rated torque meets or exceeds the calculated demand, because an undersized motor can stall mid-rise inside an inaccessible pocket
CReduce the fabric drop to lower the torque demand to 6 Nm regardless of the design
DIncrease the tube diameter, which reduces the torque required
Show answer & explanation
Correct: B. Lecture 6 warns that torque demand rises with fabric weight, drop and tube diameter, and that undersizing causes the blind to stall mid-rise inside a pocket you cannot open. Lecture 13 requires the architect to check the torque submittal before the ceiling closes. A 6 Nm motor against a 9 Nm demand must be rejected (A wrong). Cutting the design drop (C) defeats the brief; larger tube diameter increases, not decreases, torque demand (D).
Question 10
A concealed-blind schedule lists 14 openings keyed to window marks, but the boardroom blind is built to the dimensions of the adjacent office opening and does not fit. Which specification discipline from the course would have prevented this single most common failure?
ASpecifying a higher openness-factor fabric throughout
BIssuing a blind-by-blind schedule table keyed to window marks, with the manufacturer's shop drawings reviewed against it before fabrication
CLeaving the blinds as a prime-cost sum so the contractor carries the dimensional risk
DIncreasing every pocket depth by 20 mm as a universal tolerance
Show answer & explanation
Correct: B. Lecture 13 identifies the most common failure — a beautifully detailed pocket built to the wrong opening — and prescribes the remedy: a blind-by-blind schedule keyed to window marks, plus shop-drawing review before fabrication. It also warns against leaving concealed blinds as a prime-cost sum (C wrong). Fabric OF (A) and universal pocket depth (D) do not address the dimensional-keying error.